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Jason Fung explains why intermittent fasting diets work (qz.com)
275 points by prostoalex 5 days ago | hide | past | web | favorite | 326 comments





Having gone back and forth on this (a 16-hour fast for a several week period more than one time), and having read a bunch on the topic, I've concluded thus far that, fundamentally, there's no one-size-fits-all for human bodies. In other words, human bodies are so complex that results for almost any food program vary a lot.

Aside from the individual factors, which include your gender and age and whatever uniqueness about your body that we don't know yet (like effects of gut flora on metabolism), there's the type of exercise you do.

If you do long distance running or cycling, at one extreme, it's obviously a no-go. If you do a short conditioning workout or strength workout right before breaking your fast (if you're lucky enough to have a schedule that allows that), that sounds okay.

There's some speculation that fasting 'resets' the gut flora, or that there's a benefit to 'giving the digestive system a rest', then there's some science around the impact on fasting on circadian rhythm reset benefits, some other science around fasting to 'reset the immune system.'

My personal experience was that I didn't get much benefit in terms of body fat cutting, I didn't notice a performance increase or decrease in the gym (where I do strength training and calisthenics primarily with a bit of cardio). I DID notice I was obsessing over food in the mornings and when 2pm came around, there was a feeling of accomplishment.

I'm not sure it was worth it for me. As for everyone else, the jury's still out. It's just that I'm not convinced it'll be back within my lifetime in this complex area of study.


>If you do long distance running or cycling, at one extreme, it's obviously a no-go.

This isn't obvious to me. I don't run seriously, but I don't find that fasting has any adverse effect on my performance. If you are talking about running a marathon or something like that, then sure, but hardly anyone is doing exercise that intense multiple times a week, so you could still have fast days.

16 hours really isn't a very long time to go without food. Your body can cope with it fine, even if you're doing quite intense exercise.


I cycle 4 days a week for 2 - 4 hours each ride. I have tried various kinds of fasting including 16:8 and 5:2 and they've all been a disaster. I have extensive split times for the same rides and after accounting for wind/temperature, when fasted, I slow down about 3% after 90 minutes. After 2 hours, I slow down 5%. After 3 hours, I slow down 15% and feel terrible. I also feel more tired for the rest of the day. Even if I don't fast on ride days and fast on the other 3 my ride times are slower and my recovery is harder. I've kept up the fasting for at least 3 months to see if my body will adjust, but it does not work for me. Now, I practice 16:8 in the winter when I'm riding less but not during the main season.

Exactly. Your body is very good at storing energy (fat). It's also pretty good at burning fat while running, especially at the slower pace that is typical of long distance running. You can eat a couple of thousand kcal in one sitting, but you can store a hell of a lot more around your waist. Getting enough water and electrolytes during a long distance run is much more important than having breakfast beforehand.

I imagine that if you're training for an endurance-based competition, getting all of your required calories in one sitting once a day will either not happen reliably, or be really uncomfortable.

There's a lot of calorie in fats and sugars. It's quite easy to eat a single meal at some place like Carls Jr or Burger King and meet your calorie needs for the day of a run...and then some. If you eat at Cheesecake Factory, it's hard to find a meal which wouldn't satisfy your calorie needs for an several days.

Endurance training involves eating a lot in any case. It's not that difficult. Fasting for 16 hours would still give you an 8 hour window to down the foods.

It's "obvious" to those unfamiliar with fasting. Once you're used to fasting, what was previously obvious and intuitive gets thrown out the window.

Well, it was obvious to me when I started dry-heaving after going on a morning run without eating first. It was a distance/pace that I never found particularly challenging under normal conditions. It's interesting that other people seem to have no problem exercising on an empty stomach.

If you're not used to it it might feel weird. But you absolutely can do intense exercise without eating first.

Does your dry heaving mean anything other than you were feeling stress? Or that your abdominal neurons were disoriented?

>If you do long distance running or cycling, at one extreme, it's obviously a no-go.

I always do my runs in the morning, right out of bed, fasted. Your body is very good at storing energy and using it later, I've had no issues (if anything, trying to eat before a run just causes problems for me).


I found I stopped hitting walls and levelled out my pace a lot once I started running while fasted. I was doing IF for about two years while running 20-30km once per week or so, and I liked it quite a bit. Eventually I moved in with my girlfriend and her and her son found it too weird that I didn't eat with them - I'd just hang out while they ate the food I made. That's the big barrier with IF. Everyone wants you to eat, so I stopped doing IF consistently.

I had a similar experience with the social pressure around eating and fasting. I’ve had people get upset with me for doing a water fast and not joining them in eating while we’d sit around a dinner table. I workout a good amount (running, yoga, weights, swimming) and they thought I was being crazy, or they just felt judged for eating. For me it didn’t even register that highly: I’d wake up, decide to do it for a couple days to see what the effects on my body were, and that’s about it.

Honestly the hardest part was from other people, the fasting part was fairly easy and made me feel great.


Same - and I’ve recently upped my long runs to 12mi, which I do before eating anything. I’m sure there are limits where you need to fuel before or during an endurance activity, but I’m surprised and happy to not have found it yet.

I think we really over-estimate the degree to which "fasting" for less than one day affects our ability to perform. We're blessed with such an abundance of food in the west that few of us have ever felt real hunger. Your body is so far from hitting a wall after 12 hours of no food it doesn't seem to be anything but mental. I've done tons of fasted weight training and high-intensity cardio.

I grew up doing sunrise to sunset fasts for Ramadan, with no water, and even that was mostly mental.


Alternative perspective: after three hours without food during the day I begin physically shaking and have to fight an urge to curl up in a ball.

I can manage about seven hours sleep + a run first thing but I have to start eating as soon as I'm back in the house, and just keep grazing until 22:00


It would be a good idea to speak to a physician.

That's not because your current system has any problems--if it works for you, great! But that discomfort you describe is both abnormal and frequently linked to health issues that could cause serious problems over time.

Source: dietician relative on the couch next to me, FWIW.


You might want to get checked for hypoglycemia. That doesn't sound normal. (Unless you pair too much caffeine with your fasting)

The fact that you can do nighttime "fast" but get anxious after 3 hours while awake indicates it's just a mental issue as well.

Sounds like you have a serious medical problem, you should see a doctor.

You're an outlier.

I bonked out hard after going on a run after eating only a banana since waking up. Now I always make sure I've had at least a few hundred calories

That's because you ate that banana. That stimulated insulin release and your body couldn't use fat as energy.

Do you fast, though? If you're used to eating before exercise, there'll be a big psychological barrier.

my body does not work right out of bed. it takes me 30-45 minutes until I feel like I can make any exersion. if I force it I have zero energy. I don't eat first but I can't exercise right out of bed.

Sounds like Ramadan. Especially the "obsessing over food" part. Some of us actually end up fatter after the month of 16 hour fasts.

Having spent time with Muslim friends around Ramadan, I have no doubt that this is due to OVEREATING after sunset and before sunrise. I've seen people pack 3000 calories into 2 meals when they should be getting 1500-2000, especially with the reduced activity levels due to lower energy.

Fasting doesn't give you the ability to break rules of biology.


If you are "obsessing over food" during Ramadan you are doing it wrong.

> I've concluded thus far that, fundamentally, there's no one-size-fits-all for human bodies

Exactly. I've had pretty bad experiences with a no-breakfast IF. After two or three weeks on the diet, I get insomnia, and I definitely feel more stress. On the latter, I've read that IF raises cortisol levels, so that might be it. That's actually pretty good when you're at low baseline stress levels (it puts you in a state of "positive anxiety"), but when you're stressed from work it can take you over the limit.

Ultimately I stopped it because I'm already at around ~12% BF - I couldn't even say why I was doing it anymore. Three healthy meals a day and regular exercise does it for me.

If this works for people without negative consequences, then all the more power to them. I really like how it goes against the "shove things into your mouth at every waking hour" philosophy, which has become a ridiculous dogma in modern society.


If you do long distance running or cycling, at one extreme, it's obviously a no-go.

Not obvious at all. My best marathon times followed training cycles where I didn't eat breakfast before long runs (i.e., 13+ miles).


What about water fasting for longer periods? Have you gone 24/48/72 hours without any food? I find that longer fasts tend to work better for me, since I end up eating more calories in the 8 hours window in a 16/8 IF regime. But if don't eat for close to 36 hours, even with the increased food intake, I would still come out ahead.

If you fast long enough, say 48 hours I think, your body enters a mode of "autophagy", which is highly beneficial. So there's that.


I've done extended water fasting several times. 5-days, 7-days, 10-days, 17-days. It's MUCH easier for me to fast for 7-days than do 7 24-hour fasts. I feel much less hunger and fatigue when doing extended. All the negative experience is in the 1st day or 2 and gets really easy by day 3. So the result is much less net discomfort with extended fasting.

I fasted for around 40 hours once, and by the end I felt extremely low energy. I noticed I was avoiding standing, leaning on things if I did, and my normal foot-tapping or idle movements completely stopped.

Does anything like that happen to you? Do you know if it would feel better during autophagy?


I've done a 12 day fast. The first 4-5 days were extremely difficult (caffeine withdrawal didn't help) , but by day 6, I had a feeling of euphoria. My original goal was a 10 day fast, but I didn't want to give up the clear mind and energy I was experiencing, so I extended it to 12 days.

I think this is a pretty common experience. You don't start feeling the "good feels" until you get past the 4-5 day mark.

Anyway, this was about 7-8 years ago and I haven't tried again since, but I often think about it.

For what it's worth, I do IF as a lifestyle (18:6). Basically (for me) it's a very easy way to help restrict calories. Hopefully there are some health benefits, too.


Here's an anecdote:

The first time I did a longer fast (72 hours) I felt low-energy, as you describe. Then I ate a single large meal and did another long fast; that felt quite good for the duration of that fast... so I did that for a month, more or less, and lost a lot of body fay (I'm 6'4" and I went from 225 to 200).

And then I was being pretty healthy for 8 months before going back to occasional drinking, but I still don't do sweets other than fruit.

I mostly eat a single meal in the middle of the day (though I make a lot of compromises due to being around other humans) and I don't usually find myself hungry in a way that is intrusive on my thoughts. However, I did start rock climbing in a gym and I upped my caloric intake and would eat a small meal afterwards.

I did another series of fasts this spring to bring my weight down to 175, and it's stayed there. And then I did a short series of longer fasts this fall, and didn't feel low-energy during them.


Careful there with using bodyweight as your gauge. How much of that was fat versus muscle loss?

I don't have a good way to measure that, but if you have one let me know.

I can say that after all this, I was climbing hard 5.10s and easy 5.11s, and I'm 40, and I haven't been able to climb stuff like that since I was about 22.


It's very likely that it was most of it. It's just how fasting works. Your body enters ketosis in a day or two and uses fat for fuel. Your body would have to be rather dumb to burn muscle at that point.

Yes, whenever I've done 48 hour fasts, I've had the same experience. This is due to the depletion of glycogen in your liver and muscles. At that point your body doesn't have the fat-burning machinery quite going yet, so you are in a temporary dip in energy. You'd have to do another 24 hours or so, I believe, to fully enter into that state. At that point it's business as usual except that you do zero digestion. It's where all the good feelings are. At this point your body balances itself for the time being and produces exactly what it needs to in order to function. You actually get a boost of hormones and metabolism.

I believe autophagy doesn't kick in for the first 5 days, so if you want to preserve all muscle mass, that's the window to stay under. Once you go after that, the changes aren't that dramatic either, so you'll recover whatever muscle loss you incur fairly quickly as long as you're fasting while still having fat reserves. Once you're out of those, fasting is a bad idea, in the sense that you will start dying.

https://www.amazon.com/Complete-Guide-Fasting-Intermittent-A... - another book by Jason Fung that covers water fasting more in depth.


It's not like your body is going to eat its own muscle! It's not that stupid. The muscle loss is due to the normal wear and tear of daily activities. If you train hard during a prolonged fast, it's likely going to lead to more muscle breakdown. And autophagy is not that either. Also, it kicks in much sooner than 5 days.

As for fat reserves, even fairly lean individuals can probably go a week or two without food without breaking down much muscle. 14 days at 2500 calories is merely 10 pounds of fat. Unless you are morbidly skinny, you should have 10-15 pounds of fat ready.


> If you do long distance running or cycling, at one extreme, it's obviously a no-go

I did a one week Buchinger fasting and did several long distance runs (as I always do) after 2 days fasting. (after switching to cetogen burning) I noticed a small decrease in power, but in no way this was a no go. It was actually fun.


Likewise, I found my energy was slightly lower but it was also very consistent. Like burning hardwood. You don't get explosive power, but you can go steady without hitting walls.

As you point out there are cycles that will influence the experience of a fast - not limited to physical energy available at any time, possible discomfort due to coping mechanisms food/eating may part of, and so on. I am still managing significant chronic pain, and although sugar is bad for inflammation - which has its own problems - it is "comforting" and numbs the pain to some degree as well. I generally go through cycles of pure water fasting for 3 days to break the sugar cravings and to bring back mental clarity, at the cost of the remaining pain localizing and becoming sharper. Still waiting for refuge from pain, potentially some more healing next week, and then have to wait another ~3 months for another stem cell treatment.

Did you continue to eat high-carb meals after your fasting? I recently had to give up eating keto for a few weeks and then I noticed I got very hungry in the mornings. On keto I would normally eat around noon without much effort. If your body gets used to high insulin it will naturally make you crave food more often.

To all those who replied saying they fast and do long distance running, I guess I stand corrected. But I'd be concerned about muscle catabolism, as if the body is asked to retrieve energy due to demands placed on it, surely after a prolonged fast the muscle tissue is a strong candidate.

Well we're talking about intermittent fasting here. You'd gave to be pretty damn skinny for your body to have run out of fat to burn within 16 hours (max).

There are comments above about prolonged fasting (more than typical IF) and long distance running.

So Jason Fung is actually misreading this study. The main issue around all of this is: If someone eats the exact same amount of calories but spreads it out throughout the day does this have any effect on metabolism or weight? So far IF proponents have had a really hard time showing isocaloric diets have any different outcomes regardless of meal timing. This study attempts to address this issue by serving the same amount of food, but it does not ensure that the same amount of food is consumed, and so we are right back to where we are with all IF studies that show results like this: IF contributed to the participants abilities to eat the right amount of food, but there is still not a single study showing isocaloric intake and any different outcomes.

Besides that the standard: this is done on 8 people over a very small period of time, so it's at best a pilot study anyway.

IF may be a great way for some people to comply to their dietary goals better, but there is still not a single study that shows it actually does anything besides that.


>IF may be a great way for some people to comply to their dietary goals better, but there is still not a single study that shows it actually does anything besides that.

I think Keto is the same way. There isn't strong evidence of a clear metabolic advantage (I'm not saying there is not one), but its one of the few ways I have eat a caloric deficit and not hate my life.

I think if IF and Keto take people off a insulin roller-coaster and let them comply with their targets, that is still a huge win, in and of itself. We know their are other benefits too such as depletion of stored liver fat or better acute insulin responsiveness, but these may be gravy, the real win is in compliance IMHO.


The real win is compliance, and it is a real win that deserves being talked about, but that's not the point the study Fung is talking about in the article is trying to make. It specifically sets out to prove that beyond caloric deficit there are benefits to IF:

> We demonstrate for the first time in humans that eTRF improves some aspects of cardiometabolic health and that IF's effects are not solely due to weight loss.

It fails to do so because it does not measure food ingested, only food served, and so we have no idea if the diet was actually isocaloric (hint: it wasn't).

Keto and IF proponents both want to see a metabolic advantage that simply is not there. Compliance is huge, but there is no existing study showing a metabolic advantage that doesn't also have a caloric deficit.


The evidence is there though.

A caloric deficit eventually forces the metabolism to slow down, hence the yo-to effect afterwards, whereas fasting doesn’t, not when implemented correctly.

In other words, yes you have the caloric deficit with fasting, but without some of the downsides of the body going into starvation mode.

If you are to believe the hyperinsulinemia theory of obesity, it actually makes perfect sense — it has been shown that insulin inhibits the body from accessing its own fat deposits. It has also been shown that you can make anybody fat by injections with insulin, no matter how thin they are. And there are several drugs known to make people fat by stimulating insulin. These are facts.

So by eating multiple meals per day, you’re stimulating your pancreas to trigger insulin in the bloodstream multiple times per day.

Thus the body will not have access to its fat store while that happens. As long as your insulin is high, no matter how much fat you have, you’re starving without eating food.

N.b. there has been plenty of evidence of this for the last several decades. What is new is the discovery of leptin and glucagon, two other hormones that are the opposite of insulin and that do a lot to fill in the blanks and explain why insulin is having the effects we’re seeing.

Also the metabolism is slowing down on caloric deficit, with the result that people eventually regain that weight back and then some, this has been shown in many studies, including that huge one from the Women’s Health Initiative.

When you’re doing keto or fasting, the insulin goes down. Again, this is a fact.

This allows the body to consume energy from its own fat deposits. This means that the metabolism shouldn’t slow down, when implemented correctly. Having fat isn’t for good looks, but an evolutionary advantage, we are supposed to use our fat store when in need, otherwise we would have evolved to excrete the excess.

Now of course, here we are talking of healthy people. It’s debatable if the metabolism slows down or not when we are speaking of diabetics or the obese. And actually I talked with people that claimed they measure their metabolic rate and it did slow down with fasting. So it works better for some people than for others.

But on the metabolic advantage, that advantage is undeniable for diabetics at least. In the next couple of years you will hear more and more of keto being promoted in the treatment of diabetes, because it works and there’s also a large study that’s still in progress, but that promises great results.

And btw, the reason for why keto hasn’t taken off in the medical community is due to perverse incentives. Nobody wants to invest hundreds of millions of dollars in proving that a diet works, because a diet doesn’t generate profit. The cold, harsh truth is that it’s more profitable to sell statins and synthetic insulin.

Funny enough, they did invest hundreds of millions (billions?) in trying to show that saturated fats and salt are bad, anything and everything to blame, except for sugar. All such studies failed of course, but that didn’t stop the dogma, anything to keep us consuming sugar, which is where the “_a calorie is a calorie_” bullshit comes from.


> In other words, yes you have the caloric deficit with fasting, but without some of the downsides of the body going into starvation mode.

The "starvation mode" idea is thrown around a lot but is categorically not something that overweight people ever go into. The premise came from a study done on a tiny sample size in the 1950s of severely malnutritioned soldiers. It is an extreme, near death state.

> A caloric deficit eventually forces the metabolism to slow down, hence the yo-to effect afterwards, whereas fasting doesn’t, not when implemented correctly.

Citation needed, specifically on the second part. Isocaloric diets with different compositions have not been shown to have any difference in weight loss amounts.

> So by eating multiple meals per day, you’re stimulating your pancreas to trigger insulin in the bloodstream multiple times per day. Thus the body will not have access to its fat store while that happens. As long as your insulin is high, no matter how much fat you have, you’re starving without eating food.

No, this is a misunderstanding of the metabolic system. The body is very good at storing and using fat, and there is zero evidence that an isocaloric diet prevents your body from accessing fat stores. If you eat the same amount of calories, you will supplement (or not) the same amount of energy from your fat stores regardless of when or what those calories are made up of. There may be small statistically significant differences here, but there absolutely has not been a study showing clinically significant differences. Every study that has shown improvement in metabolic markers has not compared isocaloric diets, as I mentioned in the comment you are replying to. I'd be happy to look at any study you think does, but this would be a massive shift in the current understanding of metabolism and so it is unlikely such a study exists.

> When you’re doing keto or fasting, the insulin goes down. Again, this is a fact.

I'm not sure what you mean by "the insulin goes down" but basically this is not a fact because it has not been showing in isocaloric diets.

> This allows the body to consume energy from its own fat deposits. This means that the metabolism shouldn’t slow down, when implemented correctly.

Again, this is a misunderstanding of the metabolic system.

> And btw, the reason for why keto hasn’t taken off in the medical community is due to perverse incentives. Nobody wants to invest hundreds of millions of dollars in proving that a diet works, because a diet doesn’t generate profit. The cold, harsh truth is that it’s more profitable to sell statins and synthetic insulin.

The medical community is extremely messed up, but the part of it that focuses on treating obesity regards keto as a way to build compliance, but has largely read the studies and come to the same conclusions anyone else who understands the basic biology has: the premise that keto or IF produce metabolic changes outside of the ones that come from caloric deficits brought on by increased compliance is extraordinary and requires extraordinary evidence, which has not been produced.


Which study are you referring to? He references different studies to make different points and I can’t tell which one you’re talking about.

https://www.ncbi.nlm.nih.gov/pubmed/29754952

This one, mentioned in this context:

> This was a randomized crossover, isocaloric and eucaloric study. That is, all patients did both arms of the study eating the same foods and the same calories and then compared against themselves. The two arms of the study were eating between 8am and 8pm, and the eTRF strategy of eating between 8am and 2pm, but remember, both groups ate three meals per day of the same foods. Some would start with the conventional diet, then cross over to eTRF, and others did the opposite, separated by a seven-week washout period. Subjects were men with prediabetes.

> The benefits were huge. Mean insulin levels dropped significantly, and insulin resistance dropped as well. Insulin is a driver of obesity, so merely changing the meal timing and restricting the number of hours you ate, and also by moving to an earlier eating schedule, produced huge benefits even in the same person eating the same meals. That’s astounding. Even more remarkable was that even after the washout period of seven weeks, the eTRF group maintained lower insulin levels at baseline. The benefits were maintained even after stopping the time restriction. Blood pressure dropped as well.

Specifically this sentence:

> so merely changing the meal timing and restricting the number of hours you ate, and also by moving to an earlier eating schedule, produced huge benefits even in the same person eating the same meals

is incorrect, and is basically the lynchpin of the entire IF idea.


But isn’t that exactly what the study shows? You started by saying Fung misreads the study, but that’s what the study says, isn’t it?

Maybe you meant to question the study itself, but I don’t understand your objection to that either. The study tests whether this form of IF improves certain markers of metabolic health, and it shows it does — within the design of the study, of course, but that’s true of every study and doesn’t make it meaningless. You seem to be implying it doesn’t work in the way IF proponents think it does. That may be true, but isn’t relevant to this study since it doesn’t attempt to answer.


My honest read of the study is that it's a poor attempt at making a case that sets out to prove something, ignores several variables that disprove its central hypothesis (like weight loss) and then steam rolls the idea that its showing something it absolutely is not.

The study, like all similar IF studies, showed that people who do IF sometimes are able to use it to consume fewer calories. That is important from a compliance standpoint: it means you can use this diet to treat obesity for some portion of the population for whom it is going to be effective because it will get them to comply with not eating too much. Not eating as much is associated with weight loss which is associated with all kinds of good outcomes. That's awesome, but it doesn't mean that metabolically there is something significantly different going on outside of eating less.

This is an important discussion in nutrition in general, and shows up in IF as well as keto discussion frequently, with proponents of each arguing that beyond the compliance aspect, there is also something special going on with your metabolism (ie: insulin sensitivity and other metabolic markers). The problem is that all of these are things that improve when you are in a caloric defecit, and the studies never disambiguate between the effects of a caloric deficit and the meal timing itself.

Fung makes the same mistake the authors of the paper do in interpreting their own results too optimistically. The dietary controls are set up in a way to make it seem convincing in an abstract if you are familiar with this area and what the current core issues are, but it is not at all if you dig in.


Why do all wild lions look the same? Are their bodies not complex like ours?

Fasting is followed by animals too. When they fall sick they fast. Deliberate fasting in humans is a necessity because humans eat unnatural food.


Oh dear, it's not entirely clear where to even start with this.

Let's begin with the fact that we're not lions. We're not even carnivores. And there's some research evidence that in omnivores, short-term fasting leads to increased acidification in the stomach, while it doesn't for carnivores - that's a rather substantial difference.

Then, we come to the magic of "unnatural" food. We'll leave out the fact that such a thing doesn't exist and assume you mean processed food. What exactly is the proposed mechanism here where fasting is beneficial? And why can't that same mechanism be achieved via less processed food? And which processing are we even talking about?

Also:

> Why do all wild lions look the same?

Have you actually seen wild lions? They look roughly the same in the sense that "all white people look the same". I.e. not at all.


> Let's begin with the fact that we're not lions. We're not even carnivores.

It is evident we are not lions. It is also evident that we are not carnivores. Are you sure we are omnivores?

Fasting has been recommended in Eastern cultures for thousands of years. If they were bad, we would have known.

> Then, we come to the magic of "unnatural" food. We'll leave out the fact that such a thing doesn't exist and assume you mean processed food.

Processed food is unnatural. We were not designed to eat such crap. The diseases we have to endure are the evidence. Try feeding your dog or cat the same crap and they get sick too. What more proof is needed?

> Have you actually seen wild lions? They look roughly the same in the sense that "all white people look the same". I.e. not at all.

What I meant is that they look lean and mean. Not one obese lion will you find in the wild.


> Are you sure we are omnivores?

Yup. We have evolved to consume meat, as well has plant matter. You can argue this point down the rabbithole, but it's irrelevant to the broader point. If you want to say we're herbivores, fine. Lets not get lost in that debate.

> Fasting has been recommended in Eastern cultures for thousands of years. If they were bad, we would have known.

So has circumcision. I say that as someone not categorically opposed to it - but to say that just because something has been done a lot, doesn't mean it's not harmful.

> Processed food is unnatural....

Processed food is not harmful on account of being processed. It's can be harmful for what it contains. Most food is processed.

I assume you're talking about weird nasty foods. I don't have a proper label to define them by. Things with a ton of Hydrogenated Oils, or whatever is inside "Cheez Wiz"

> Try feeding your dog or cat the same crap and they get sick too.

For your very broad statement of processed food, this isn't true. I mean, dog food itself is processed. For food that the animal should not be eating, yes. That'll make them sick. Dogs can't eat all human food. Humans can't eat cow food. A dog will get sick if it eats chocolate. A human will get sick if they eat nothing but grass.

> What I meant is that they look lean and mean. Not one obese lion will you find in the wild.

That's caused by external factors, not because a wild antelope isn't "processed" or "unnatural". You can feed a lion antelope meat until it is obese. But it has evolved to be in a healthy balance when it exercises through hunting, and its intake is limited by the available prey.


> We have evolved to consume meat, as well has plant matter

OK. Let us not argue this point.

> So has circumcision. I say that as someone not categorically opposed to it - but to say that just because something has been done a lot, doesn't mean it's not harmful.

This assumes that ancient cultures were naive and we are too evolved to even bother about our ancestors.

> Processed food is not harmful on account of being processed.

I would recommend you to read the WHO report that puts all processed meat under category 1 carcinogen. Processed wheat, rice, oil... everything has been proven to be harmful.

> I mean, dog food itself is processed

That is because we are involved. It does not have to be. Raw meat is available and is natural for them. Dogs and cats raised in urban world are obese and have health complications like humans. Diabetes, heart diseases are common.

> You can feed a lion antelope meat until it is obese.

Sure. Good food and no exercise is a bad combination. Bad food and good exercise is also not a good combination.


Cooking explicitly does not count as processing, so no need to eat raw.

And raw red meat is a category 2a carcinogen.


> And raw red meat is a category 2a carcinogen

That makes it safe to consume?


> Are you sure we are omnivores?

Yes, you can look at our digestive system and teeth to see clear omnivore adaptations. Both are closer to say bears than either cows or lions.

What's really interesting is lions for example can't grind their teeth.


I am not so sure. A mouse does not cook flesh, we do. They eat rotten flesh too. The day humans can eat uncooked\rotten flesh and not fall sick, I will consider us to be omnivores.

Stake tartare is raw beef: https://en.wikipedia.org/wiki/Steak_tartare

'dry-aged beef' is still rather sought after. "The process of dry-aging usually also promotes growth of certain fungal (mold) species on the external surface of the meat. This does not cause spoilage, but rather forms an external "crust" on the meat's surface, which is trimmed off when the meat is prepared for cooking." https://en.wikipedia.org/wiki/Beef_aging

https://honest-food.net/on-hanging-pheasants-2/

I could go on, but people can digest uncooked or well aged meat. It does have a higher risks, but that's more about how meat is raised and prepared not necessarily simply being old and uncooked.


Stake tartare is a dish. Ground raw flesh mixed with other ingredients. Cannot count this.

> 'dry-aged beef' is still rather sought after. "The process of dry-aging

"The process of dry-aging"... Processed. Cannot count this too.

We do not have protein receptors in our tongue. We cannot taste flesh the way carnivores and omnivores can. They do not need to cook, add spices, process flesh. Raw meat can kill us.


> mixed with other ingredients

such as the dreaded raw egg. The only thing making this easier to digest is the grinding part.

Unprocessed entire raw and often living fish are regularly consumed as part of fraternity initiations and bets. It does not cause problems.

Cooking increases food safety, but it's really not required for digestion.

PS: To use a slightly older tradition. People used to do something similar in Europe. Hang birds up by the neck, when it fell down it was 'ready'. Calling that processed is ridiculous.


People have done and do stupid stuff. What's your point?

The point is that you brought up rotten meat. And then proceed to call any rotten meat we still consume "processed". That's intellectually dishonest.

You might want to look up "Stinkheads". Dry-aged beef. "Haut gout". "Hákarl"

But that's not even germane to a discussion. Omnivores are not necessarily scavengers, nor does it mean that they eat literally everything. It means they eat meats, and plants. (Look e.g. at the maned wolf for another example of an omnivore that pretty much avoids rotten meat. They get 50% of their diet from - fresh - prey, and 50% from plants. That makes them an omnivore)


Most omnivorous and carnivorous animals can get sick from uncooked flesh too.

Animals also eat their own throw-up, that doesn't mean we should too.

Lion diets haven't changed since lions became a distinct species. Human diets have changed drastically in the last 10k years. And there are well known examples of humans evolving adaptations to changing diets (lactase persistence in Northern Europeans being the most obvious). It would be crazy to think that other, less obvious adaptations to diet haven't occurred in basically every other region with a distinct diet.

Also look at osteoporosis rates in Western cultures. Lactose tolerance\intolerance is the term. I can smoke 20 cigarettes a day and my body tolerates that. Does not mean it is good for me.

Lactase persistence is the name of the trait that makes a person tolerant of lactose:

https://en.wikipedia.org/wiki/Lactase_persistence

And I’m not sure what you thought I said, but I’m not arguing that milk consumption is great. Well, not in the post you responded to; I do think milk is pretty amazing. All I was saying is that it is an example of humans evolving adaptations to their diets.

But on the topic of milk consumption: there may be drawbacks, but the gene for lactase persistence is one of the fastest spreading genes in recent history. Consuming milk was an utter (there’s a pun to be made here, but I will exercise restraint) game changer for Northern Europeans. Even today, milk is an amazing source of well-balanced nutrition. It’s cheap, easy to consume, and pretty tasty at room temperature.

If it doesn’t cause explosive things to happen to your intestines, that is.


My point is that body will adapt to all situations. Smoke your first cigarette and body revolts. It becomes progressively easy. Body adapted. Is it good?

Same with milk, meat, sugar...


My experience with time-restricted eating has been that, regardless of the benefits of the fasting itself (which FWIW I do believe in), it has brought one significant change into my life: caring much more about the nutrition of each meal I eat.

Before I began fasting, I found myself saying things like, "Well, this isn't great for me, but it'll be filling for a few hours and then I'll eat something else." With IF that is not an option, and it forced me to more carefully consider whether I was providing my body with the proper fuel for the next X hours.

Similarly, coming out of the fast, I was much more likely to eat nutritionally-valuable foods because I knew that whatever I put in my body it would immediately consume for fuel and I wanted to give it something valuable.

That in itself has led me to rave about IF to anyone who is interested enough to listen. I recommend at least an experiment with it to experience that consideration of nutrition, because I think that will stay with you whether you stick with IF or not.


I'm 485. I had gastric sleeve surgery in 2012 at 650 (after losing 40 through liquid diet).

5 weeks ago I was 515. I started a fitness challenge at a CrossFit gym, I workout 4 days a week, I eat Keto, and I (sometimes) eat just one meal a day. I find it really hard, like extremely hard when doing IF to get all my protein in for the day.

I kid you not, because of my stomach size, the keto effects (lower hunger), and only having an hour or two window for food when I stick to IF completely I can't get more than 50 protein, and 600 calories.

This week, I've modified it to fit my body, I've added body fortress protein which 1 scoop in almond milk = 8 carbs, and 60 protein (my daily minimum). I eat this around 11 or noon. Then I try to have my 1 meal at 5pm. Is it IF? Not completely, but I feel for me it works a lot better.

I can probably still get only 600-800 calories a day; example: 2 burgers + 1/4th cup cheese and a dab of mayo and I'm stuffed to capacity, it takes an entire hour to finish this much food, but at my weight that's no biggie, the biggest thing is getting protein so my weight lifting at CrossFit has good results.

I'm no expert on physiology, so if anyone has tips to maximize my progress (I'm about losing more (fat) and gaining more(muscle) as fast as humanly possible).

Physically I feel like a million dollars, depression is mostly gone and anxiety as well. I'm a little obsessed on my diet/exercise regime, not sure that's bad. I started taking Vyvanse for ADHD so that also curbs appetite/hunger and has helped me focus more on my code/work. Last year I had major depression with dark thoughts, this year I feel like a different person, I'm also seeing a therapist for that stuff as of a few months ago.


Because you've had that surgery and your stomach size maybe intermediate fasting isn't the best way for you in the end?

Instead a high fat low carb diet where you really minimize carb intake (and obviously avoid all things sugary). You can get the same keto effects if you follow this approach.

This way you can easily eat several times a day and get all protein and calories you need.

Of course you can mix and match IF with this as well.

> I'm a little obsessed on my diet/exercise regime, not sure that's bad.

Be mindful. Obsessions always lie at the edge of turning bad.

Also if you've only done this 5 weeks it's easy to do too much too soon and if a time comes when you can't hold the same extreme tempo you risk a crash. This has happened to me many times. For example I've started a new training form and I train it a lot. But then I don't have the same drive like last week and a miss a single training. Then another one and suddenly I haven't trained for a month.


Thanks for the advice.. I think I'll keep trying this diet regime for a little bit, I like how I feel w/ it...

Definitely see your point w/ obsessions... I over analyze and think things. I also try to optimize everything as a developer that's just what I do lol..

I do have a fear that as winter comes I might slack off more on workouts, esp since my gym is 30 mins away (I live in podunkville,UT), so increment weather could affect my sojourn to the city to workout. I'm hoping I just let things go more, and it just becomes part of my life, at least till I hit my goals.


I am not an expert on psychology, but your goal "losing more (fat) and gaining more(muscle) as fast as humanly possible", might be detrimental to your success.

It probably took decades to get to your current body weight. Should it not then take at least 5 years to get back to your target weight ? True the caloric math shows you could probably get to 250lbs in a year with a 600-800 a day diet. But can any human actually stick with that diet for more than a month ? If not, you would be better eating 1600-1800 a day if you could stick with it for a year.

As an aside, at times I wonder if our obesity epidemic is in part related to an ever increasing target/acceptable weight. When I was a kid, if you could pinch an inch, you were overweight (I stop drinking calories if I pass the threshold). Even my childhood bathroom scale maxed out at 250 which implied that 250 must be extreme morbid obesity.

I know this is personal, but when you were young did you ever have such thresholds (weight, mobility, etc.) in mind ? Or did it just sneak up on you and by then you were in gaining weight at a surprising rate beyond your control ? No worries if you are too busy to respond. I wish you the best!


I don't think it took decades... I was 410 at 14... that's a decade/half maybe... but I was always obese...since birth practically. (80 @ 6, 300 @11, etc..)

There is some good evidence (both studies and anecdotal) that there is some muscle memory in the sense that it's easier to regain muscle that was lost than to build it in the first place. So even if you lose some muscle during this whole thing, you should be fine. You want your body to be in as much in ketosis as possible; it has a huge reserve after all.

I'm sure you've seen or heard of this case study of the Scottish man who fasted 382 days [pdf]! Of course, he did it under medical supervision. But I think it's an important case of what CAN be accomplished.

[pdf]: https://pmj.bmj.com/content/postgradmedj/49/569/203.full.pdf


Thanks, that's good to know... I think w/ the added 60g of protein per day --esp on workout days, I should be okay hopefully. Might lose some, but not a lot of muscle...and I think the ketosis will definitely help tone me up as well along the way.

I have no advice, but applause and encouragement. Keep going and congrats on your progress so far. Don't stop or get complacent - you can be a motivator for other people and your progress can be a positive force for more people than just yourself

Thanks, I appreciate it. I feel great, I love Cross Fit -- the community has been VERY supportive and the box I go to is VERY good at modifying workouts -- I can't get down on the floor yet, or do lunges for example, but I still get my ass handed to me.

You're going to find a ton of people countersignalling Crossfit, and I'll admit it doesn't look like it's for me, but keep it up. You're going to be one of the success stories.

I was nervous as shit to start. It looked hard, and without modifications I def. couldn't do it, but it works if you just do it. It's not nearly as bad as the videos make it seem...

Congrats! For the long run you might consider throwing in a day with multiple meals and significantly higher calories every now and then, sticking to whole foods for the most part. This might be good for your micronutrient intake (which I'm pretty sure does not cover the RDAs on 600-800kcals) and your metabolism, which might get wrecked in the long run otherwise.

I can recommend cronometer.com for tracking food, this might be a pain in the beginning, but gives you good insight on what your nutrient intake is. Helped me to create a diet with roughly balanced meals.


I track everything on MyFitnessPal currently. I also take a multi-vitamin and Vitamin D3 daily. I did think about doing some carb loading, and I think I might try it when I hit any stalls. So far things are going good though.

I'm not a nutritionist or broscientist, but of what I do know, what you are doing now is correct, and probably qualifies as a muscle-sparing fast.

You can eat more protein--likely in drinkable form due to your sleeve--to try to gain more muscle, or you could stay the course to lose the fat first. Since lean muscle mass increases your base metabolism, which increases your fat-burning rate, that's a complex equation that may require calculus to optimize, and your body can always just arbitrarily veto the mathematical results.


Thanks, I'll try the added protein shake + OMAD food-wise for a week or two and see how it works... I'm thinking it'll be better than just the OMAD with less protein/calories. If I need to, I could even adjust to 2 shakes/day and a meal in the evenings.. Maybe push my shakes to b/w 2/5pm and eat by 7, so I'm still doing a 6-8 hour feeding window.

Dr. Dominic D'agostino & Dr. Layne Norton did a podcast on Joe Rogan recently.

https://www.youtube.com/watch?v=u93oh9kC-rU

In the course of the podcast, they discuss many areas of research that would be interesting to your question of maximizing your weight loss while maintaining health.

They also discuss what the research in these areas indicates works and what doesn't seem to matter. A lot to unpack but certainly helpful.


Thanks, I'll check it out.

Hey, have no references easy here, but you might not need that much proteins while losing weight. Fasted, your body breaks useless cells to get more protein when needed.

Just a heads up, most Body Fortress protein powders that I've seen are actually 60g per 2 scoops, not per scoop. Their marketing on the front is super misleading.

Fuck their marketing.. .I knew it was too good to be true.. double checked it earlier when I was putting it in myfitnesspal... I'll search around for a better deal.... I was using Dymatize which has more servings per bottle for 30g proteins... and a lot less carbs...

I just buy pure whey protein isolate. I blend it up with this and that. Some dates and almonds with vanilla extract. Yesterday I did hazelnuts and an apple with some cinnamon.

No added sugar, and everything pretty natural. The isolate I buy is pricey cuz it’s from grass fed cows but there are cheap ones.

Need a good blender tho.


I've got a ninja, it works really well for blending drinks.. I like to add almond milk, 2 tbsp heavy cream... if it's got no carbs I'll add some monkfruit as well. I'll have to look for some better protein isolate..unflavored I could probably cook with as well for added protein.

I suspect there's no objective way to discuss a topic while it's in the hype cycle. Mindnfulness meditation seems to have dubious benefits, the uberman sleep cycle has all but disappeared, but during their hype cycles there was no way to sit down and discuss whether they actually do anything. There were too many people singing praises and making tons of claims, and there's really no way to dispute them. The science seems to never happen on these types of things as well, so just waiting doesn't seem to be the answer either.

For all we've done in science, it seems like we still have a huge correlation != causation issue.

I just had someone tell me that the amount of auto accidents increase between 2 and 4pm in the US. This somehow showed that people make poor decisions during that time because of our sleep cycles? I was met with much resistance when I pointed out that there are fundamentally different people driving during 2 and 4pm than 8am or 5-6pm. The numbers don't lie, right? Just how you read them...

Anyway, I'd love to see the science that mindfulness and meditation have dubious benefits. I am such a believer in those practices, I have a hard time understanding the argument that they are not beneficial.


https://www.scientificamerican.com/article/wheres-the-proof-...

> The new paper cites a 2015 review published in American Psychologist reporting that only around 9 percent of research into mindfulness-based interventions has been tested in clinical trials that included a control group. The authors also point to multiple large placebo-controlled meta-analyses concluding that mindfulness practices have often produced unimpressive results. A 2014 review of 47 meditation trials, collectively including over 3,500 participants, found essentially no evidence for benefits related to enhancing attention, curtailing substance abuse, aiding sleep or controlling weight.

> Van Dam acknowledges that some good evidence does support mindfulness. The 2014 analysis found meditation and mindfulness may provide modest benefits in anxiety, depression and pain. He also cites a 2013 review published in Clinical Psychology Review for mindfulness-based therapy that found similar results. “The intention and scope of this review is welcome—it is looking to introduce rigor and balance into this emerging new field,” says Willem Kuyken, a professor of psychiatry at the University of Oxford in England, who was not involved in research for the new report. “There are many areas where mindfulness-based programs seem to be acceptable and promising, but larger-scale randomized, rigorous trials are needed.”

>As Van Dam and his co-authors wrote, “[there is] neither one universally accepted technical definition of ‘mindfulness’ nor any broad agreement about detailed aspects of the underlying concept to which it refers.”


That’s not evidence. By your logic I could disprove general relativity just by doing bunch of flawed studies on the subject.

I didn't say it was evidence, I said "Mindnfulness meditation seems to have dubious benefits", and the quoted article outlines specifically the lack of evidence around the benefits of meditation. I'm perfectly comfortable standing by this conclusion from the lack of evidence as outlined in the quoted text.

The biggest problem is many of these practices are often done and discussed in relative isolation of other holistic practices.

Intermittent fasting seems like it'd wreck your body if you do moderate to intense exercise. So I just fasted, and now I want to do intense cardio.... but I might run out of glycogen or blood sugar. Or I may do a set of weight lifting, but not if I can't eat protein after. So if I do intermittent fasting, I have to come up with a complex schedule to follow in order to get any performance gains.

The whole point of a diet is to be healthy. You don't need intermittent fasting to be healthy. It seems to just introduce complication for a menial improvement in a few measures of health. I'm sure they work, if you can actually stick to them, but there's a lot simpler diets that will also work.

Exercise three times a week. Eat lots of plants. Keep your fat, protein, and simple carb levels within reasonable limits for your age, height and sex. That's not super complicated to follow, and it can fit into basically any schedule.


Nah, that's complete BS. Fasting doesn't impair you to the degree you're implying. It takes a good 24 hours to run out of liver glycogen, and even then it's not like you keel over, you just have maybe 85% of non-glycogen-depleted performance. Just have a meal at some point the day before your workout, and you'll be good to go. Blood sugar is also a non-issue when fasting. It is in fact more stable in a fasted state due to very steady insulin levels. Humans are not fragile creatures that need to eat every X hours to do physical tasks.

I do heavy weight lifting in the early morning and fast every day until 2 PM. You don't need to eat protein right after you lift weights, later in the day is perfectly fine. For you optimal gains, maybe, but for gains, no. But I'm not a world-class athlete, I'm a 31 year old with an office job. Intermittent fasting is very popular in the weight lifting world, and it works very well. In my experience, lifting in a fasted state impacts my performance 0%.


> lifting in a fasted state impacts my performance 0%

Based on my own experiences, I'd actually expect performance to improve since the body isn't using resources for digestion. I'm not a weight lifter, but I know bicycling is significantly harder shortly after eating and my other current sport, freediving, is much, much easier after fasting (my static hold time is close to 2 minutes longer when I haven't eaten in the past ~12 hours).

One interesting observation I've had from freediving is that some of the signals we get from our bodies are far less urgent than we tend to experience them. The main one, in that sport, is the urge to breathe and it's actually not an indication that the body needs oxygen. It is, instead, an indication that CO2 is building up and you can expell it by breathing. Freedivers learn to experience that sensation and push past it.

I'd imagine hunger is very similar. People accustomed to eating whenever they're hungry will panic an experience "low blood sugar" when they don't immediately respond. But we know that humans can go weeks without eating before we die. Pushing past our accustomed non-resistence to hunger will likely be uncomfortable, at first, and then become normal with practice.


"I'd imagine hunger is very similar. People accustomed to eating whenever they're hungry will panic an experience "low blood sugar" when they don't immediately respond. But we know that humans can go weeks without eating before we die. Pushing past our accustomed non-resistence to hunger will likely be uncomfortable, at first, and then become normal with practice.

"

Exactly. People are way too used to eating all the time.


>I'd actually expect performance to improve since the body isn't using resources for digestion

This is exactly what I've noticed as well. Even a few hours after eating my runs feel sluggish. All my PRs are from running first thing in the morning, before any food.


This matches my personal experience. I found the gains acquired while IFing - exercise at around 8pm after work and fasting afterwards until noon the next day - to be very consistent and lean.

Same I do time boxed intermittent fasting, usually exercise in the morning, and eat a single large meal between 2-7PM. I primarily do cardio (distance running), and didn't notice any performance hit.

Early on when I was still experimenting with the diet, I did drop down to around 160-165lbs, and my running performance took a drastic hit. I remember struggling to complete a three mile run one day, when 6-10 was typical for me at the time. I felt normal up until around one and a half miles in, then I hit a wall, which made me turn back early. It was a really odd sensation, the will was there, but I was weak, almost like I had run out of gas. I'd tell my legs to move, and they'd barely follow through. This wasn't soreness, or fatigue, but weakness, subjectively a very peculiar sensation, and not at all subtle.

Being weak like that did freak me out a little bit. I simply added more calories (ate more), while maintaining meal timing, and my distance was back to normal in a week or two though (actually slightly better than my pre-diet "normal"). This brought my weight up to a steady 170-175lbs, which I've been at for about two years.

It's really important with this style of diet to get adequate nutrition. If you're eating less, or timing your meals, you really need to maintain a high-quality diet. You're likely eating less than most other people (or what you're used to), so the nutrients and calories you do take in are that much more important. Eat a lot of fresh vegetables, moderate carbs, and high-quality protein. Extra fiber is also really important, because the extra volume helps create a sensation of fullness, making the diet easier to stick to. You'll also want to drink extra plain water, to accompany the fiber, so your body chemistry doesn't get out of whack. Don't eat any refined sugar at all, it's a powerful appetite stimulant, and will make the meal timing much much harder to stick to.


Doesn't ketones... work roughly the same as glycogen? I'm doing keto + IF (modified, I have a noon'ish protein drink, and then a meat heavy dinner). Just wondering if you've heard that, I'm new to working out (started at 515 down to 485 in 5 weeks, lots of muscle gains too though so fat loss is probably a lot better than if I'd just dieted alone.)

Edit: I mean, I read an article once that said ketones could enhance performance in weight lifting.. my exercise is Cross Fit training at a Crossfit gym.


Intermittent fasting is probably fine as long as you only have an hour or less of exertion on that day. Do 2+ hours though and I think it's a pretty bad idea.

And in my experience even just doing an hour of exercise in a fasted state can dramatically impair my immune system as well as higher brain function.


I don't know 100% for sure, but I think this may have more to do with how many calories you're eating over time total vs how much you eat near exercising. A caloric deficit on its own will do all the things you've named regardless of feed windows, and I haven't experienced any of them while intermittent fasting. But I can't say for sure if I've ever had 2+ hours heavy exertion while doing IF.

It's not really that hard to do intermittent fasting. You just eat dinner at 6-8 PM and then skip breakfast and eat lunch at noon.

And IMO the "risk" of bonking is hugely overblown, the worst case scenario is you're in a bike race and you have no energy. Most people are not racing bikes, so I don't see what the big deal is. You stop your workout and eat something. Most people's cardio workouts are not long and intense enough to bonk in the first place, even if they're fasted for 16 hours.


I've bonked riding bikes multiple times even when not fasting. I don't see it as a risk, you just limp home @ 20km/h. Sure it sucks :)

> So I just fasted, and now I want to do intense cardio.... but I might run out of glycogen or blood sugar

Isn’t that where ketosis comes in? Your body can break down fat and provide energy through ketones.

Some proponents of intermittent fasting would probably argue that simply not eating at certain times is the simplest diet of all since it doesn’t require continually evaluating at each meal what a “reasonable” level of intake is.


Fasting followed by cardio is a thing. It's called "bonk training". Running out of glycogen is the whole point of it.

It supposedly helps your body make the switch from glucose and glycogen to body fat and ketones more smoothly. It might have been useful for triathletes and marathoners, if they weren't eating glycogen gel during their races now. You'd carbo-load, hit the wall at mile 20 or so, and just keep going at 80% your normal athletic capacity instead of 70%, because you trained for it. But now, you'd just be left in the dust by someone who has been sucking on a tube of glycogen gel and thus never hits the wall at all.

I suppose it would still be useful for weight loss, if exercising while bonked wasn't self-torture.


It takes between 2-10 days to reach ketosis and switch from using carbs for energy to using ketones. Burning ketones also brings less energy than burning carbs, which would not be ideal for cardio.

There are studies on keto-adapted athletes doing cardio, from what I can tell there is no detrimental effect from a ketogenic diet after about a month of adaptation:

https://www.sciencedirect.com/science/article/pii/0026049583...


Thanks for this, I'm doing a modified fasting regime + keto + crossfit. I started at 515#, 5 weeks ago. I'm 485 now. I have a smaller stomach from surgery in 2012 but I only lost 150 pounds after surgery (650-500). I've been yo-yoing between 450/510'ish.

My daily diet is basically a 8 carb protein shake with 60g protein around noon. Then the equivalent of 2 hamburger patties and 1/4 cup cheese for dinner. My calories rarely exceed 800 though. I feel great -- more energy than ever, and I have 0 hunger, I have to force myself to eat.

I'm hoping this is maintainable and that I can keep the momentum up. My wife has a baby due in January (our 2nd), and I want to be able to do more with the family/kids and be around for them. Luckily I have no co-morbidalities, I just did a full physical -- everything is perfect # wise blood pressure, lipids, vitamins (except D deficiency). But, I'm 38, that could change. My heart could get stressed from the weight in a few years... I've been seeing a therapist for depression, and a doctor for ADHD, and now doing a good fitness regimen.

Last year I was depressed with very dark thoughts, this year I feel great and in more control.


You don’t have to be in ketosis to burn fat for energy. Ever notice how cardio gets harder about 45 minutes in but then gets easy and you can go on for hours? That’s your body running out of stored carbs and switching to burning fat reserves.

you can't go as fast

> Intermittent fasting seems like it'd wreck your body if you do moderate to intense exercise.

That just seems highly unlikely from an evolutionary perspective: food sources for most animal species tend to be inconsistent and require physical exertion to exploit (especially for predators).

If hungry + physical exertion = damage, you'd expect that to get weeded out of the gene pool. Human populations have certainly gone through regular famines and starvation during our history, while still needing to farm manually.


If you aren’t diabetic, you need to do hours and hours of intense cardio to Bonk (run out of glycogen).

As long as you’re not doing whole day fasts, I don’t think the burden of effort is any higher than the protocol you’ve outlined.

When beginner discipline is the subject, simple rules tend to work better. Your confidence following simple rules allows you to then tolerate more complicated regimes.

Edit to add: Personally, I don’t agree with ADF but for strength training your muscles are rebuilding for days afterward. If you’re trying to gain muscle quickly you’ve probably already decided ADF isn’t for you. But to maintain or gain slowly? I’m not sure it’s going to slow you down that much.


I'm not familiar with the term bonk, but I thought the glycogen in each major muscle ran out after about 20m? I've read many times that during cardio the body starts burning fat only after the first 20m. Then it releases a chemical to begin burning calories from fatty tissue.

Your liver also stores a significant amount of glycogen that it can release into the bloodstream. "Bonking" is a term from endurance events, for example in a marathon bonking typically takes place around 20 miles into the race when runners have been running for more than 2 hours, which fully depletes their glycogen stores. Modern runners typically refuel with carbohydrates, drinks/gels, to delay bonking, but depending on pace and time you typically can't consume enough calories to fully replenish what you have used and will bonk eventually. Then you will need to continue at a slower pace burning fat for fuel.

I’m an ex cyclist but occasionally I like a bit of nostalgia. This recalls to me one conversation with a coworker who pointed out that while exerting yourself you can only absorb around 600 calories an hour, but as we know, you can burn thousands.

You have what’s in your muscles, liver, stomach, and whatever your body can cannibalize from fat and muscle. If you go long enough (without overdoing it) you start burning muscle, which is a really good example of why recovery and pace matter so much. And why runners and cyclists have those wiry little arms.


Friday99 gave a pretty good explanation but to offer a little insight into the experience: your brain runs on glycogen too. The Bonk is what happens when your glycogen stores crash so far that your mental capacity is diminished.

Smart communities train their members to watch for heat exhaustion, heat stroke, and bonking, how to tell the difference, and how to care for people in these situations.


The rules are psuedoscience peddled by health gurus.

Totally anecdotal but I lost 40 pounds in 4 months with IF and I still worked out 4-5 days a week in the mornings. I found it very very easy to follow and my body had very little trouble adapting

"in the mornings". That's exactly the point.

I eat once a day. I run almost every day. I lift weights at least every other day. I have been doing this for years now.

Our ancestors didn't get three meals a day. Millions of our contemporaries get real physical work done without three meals a day or worrying about glycogen or blood sugar. I may be an extreme example, but people worry way too much about skipping meals, in my opinion. It seems like a rationalization for avoiding hunger.


>Intermittent fasting seems like it'd wreck your body if you do moderate to intense exercise. So I just fasted, and now I want to do intense cardio.... but I might run out of glycogen or blood sugar.

Have you actually tried working out in a fasted state? I find that I get better performance.

Glycogen isn't depleted as quickly as you think, and blood sugar levels are actually more stable in a state of ketosis when your body is manufacturing its own glucose.

>You don't need intermittent fasting to be healthy.

Semantics, but I would say you do if 'intermittent fasting' just means periods of respite between meals so you're not constantly in a 'fed' state. It's only relatively recent in human history that we are even able to be constantly eating.

>Keep your fat, protein, and simple carb levels within reasonable limits for your age, height and sex.

You say this, but experts have all sorts of contradictory recommendations for what are 'reasonable' macro limits.


"Intermittent fasting seems like it'd wreck your body if you do moderate to intense exercise. So I just fasted, and now I want to do intense cardio.... but I might run out of glycogen or blood sugar. Or I may do a set of weight lifting, but not if I can't eat protein after. So if I do intermittent fasting, I have to come up with a complex schedule to follow in order to get any performance gains. "

That's not true. You just have to get used to it. When I did boxing I often did two hours intense workout in the evening and didn't eat anything after or hours before. No problems.


The human body is a stunningly complex evolved system. Intuitive reasoning at a trivial level doesn't really tell you much.

Intuitive reasoning should be suggesting to the parent comment that it would be a huge evolutionary disadvantage if there was no energy available after a short fast.

I participate in IF and lift weights after work most days. I think it's mostly about timing. I'm usually done eating for the day around mid afternoon and feel fine working out after work. You don't need protein after you workout. You will be fine if you get enough protein throughout the day leading up to your workout.

Were you able to sleep without problems? The biggest problem for me was not being able to sleep or waking up in the middle of the night due to hunger.

I just finish a 21 day water fast yesterday - it’s the first time I’ve done it. My sleep was only slightly affected. Not because I was hungry, after 3 days your appetite more or less subsides. The only notable thing that happened as it relates to sleep is that I would only sleep for 5.5 hours and my body would wake up, not groggy or tired. Typically when I eat “normally” I get about 7 hours.

After a couple weeks I stopped thinking about eating until it was time to eat in the morning. Your body gets used to it. You just have to power through the adjustment period.

There's a rather large movement of strength athletes using intermittent fasting as a tool without these issues.

Glycogen stores aren't easily depleted by day to day life, a regular 8 hour window every day wouldn't affect your evening weight lifting routine. It could affect post-workout only by increasing the time for the glycogen stores to be refilled, but not to such an extent that it would affect your next session.

As for protein after workout, this is largely nonsense. The body is more than capable of regulating it's own protein synthesis over the course of days with both the protein you obtain from food and the stores of broken down proteins from your body. Amount of protein consumed (and type) is the relevant factor and timing plays no significant part unless you are a at a level where you are considered a pro athlete and you're probably attending competitions.


"So I just fasted, and now I want to do intense cardio.... but I might run out of glycogen or blood sugar."

I used to think like this, but then I actually tried it and found that not only does a short (16-18 hour) fasted state not negatively impact my workouts but it improves my performance to exercise in a fasted state.

Heavy squat/deadlift day at the gym ... 2 hours of BJJ ... 10 mile run ... these are all examples of things I do in a fasted state. You have no bloodflow diverted to stomach (or other digestive processes) you are fast and light on your feet and your energy is very steady.

Would I embark on a triathlon or an ultra ? Of course not - but whatever fears I had about fasting throwing a monkeywrench into my training were unfounded.


IF is actually a simplifier: skip breakfast. If you don't late-night snack, just skip breakfast and you're doing IF.

I've been skipping breakfast for at least 5 years. Assuming the average breakfast would've cost me 5 minutes per day, I've saved over 160 hours not doing breakfast over those years, never-mind the cost-savings and simplification of life that comes with consuming things less frequently.

I've been healthy and fit the entire time I've been skipping breakfast, maintaining a steady weight of 175 lbs at 6'1". I usually have had caffeine, though I occasionally wean myself off. Caffeine (black coffee, straight tea, no sugar) helps with the hunger/IF lifestyle, but it's by no means necessary.


This gentleman has been doing IF for 5 years and he appears to be doing intense exercise.

https://youtu.be/dW_99QcCTzE


You can lift and do cardio just fine even on full blown water fasting for a couple of weeks, or longer if you're already heavily overweight.

It's not the most pleasant feeling in the universe, and your performance won't be anything to write home about, but you will still be pretty functional. Humans have had to go without food for a while for most of their history, so it makes sense we would have adapted to live just fine through periods of scarcity.


I do IF. I bike to work each day and work out in a gym irregularly. I have either 1 large meal or 2 small meals in a feeding window each day. I will eat right after cycling in the morning, or right after working out. I don't usually eat after cycling at night. I might have some protein or a small cup of milk at night though. Not technically IF, but also not riding that blood sugar wave all the time either.

Nope, it doesn't wreck your body, not even close.

This is because of homeostasis. You normally have close to, iirc, 2000Kcal floating in your blood, intracellular fluid, & cells. If you get too much more, then the pancreas will produce insulin to stimulate your body to store the excess as fat.

But when you are temporarily under-fed as with Intermittent Fasting or Time Restricted diet, the insulin simply doesn't arrive to force it out of the bloodstream so it can maintain the levels; levels can also be restored by converting fat stores to maintain the appropriate blood sugar level.

So, you've always got something like that ~2000Kcal store ready to go, and you don't need to worry about 'bonking' on any normal workout with any normal IF or TR diet.

I personally did once manage to do something like you worry about, during off-season training one year in my career in international-level alpine ski racing. I did a 3-day fast, with a solid weight workout (including big muscle groups) on Day#1. No problem. Then, at the end of fasting Day#3, I felt really energetic, so broke the plan and did another really heavy leg weight workout, which went great. However, about an hour+ afterwards, I felt really wobbly/shaky from low blood sugar. This was fixed with a single big orange juice smoothie. It was really cool to feel it take effect -- within minutes. And, there was no break in the training routine after these events, just continued on as usual.

Admittedly it's a single test, but it shows that it can take a lot more than one workout on a TR or IF day to even get to an out-of-the-ordinary state, and it's easily fixed when you do. Not really anything to worry about.

[Edits - clarity, commas]


Perhaps IF will allow you to complete your workout but with no where near optimal performance.

I got stronger and was able to run longer and further when I ate one meal a day. I went from a slow 1 mile run to fast 2 mile run and ended up at 3 miles by the end of one month.

Plan better. If you don't like to train fasted, then plan your fasting / workouts for an hour after you eat. That way you can also have a post workout meal.

As always for this kind of article, some of the comments have turned to more general discussion of human diet and metabolism. There was an very interesting article relevant to that in Vox.com a little over a month ago [1]:

"What I learned about weight loss from spending a day inside a metabolic chamber"

[1] https://www.vox.com/2018/9/4/17486110/metabolism-diet-fast-w...


Thanks for sharing; really enjoyed this.

Given that poor sleep quality exacerbates insulin resistance, it is possible that by not eating late into the day, the research subjects in the article's fasting study may have also lost weight because their sleep improved.[1]

Personally if I eat dinner after 5PM, I have trouble sleeping.

[1] https://www.ncbi.nlm.nih.gov/pubmed/21950773


I dislike articles like this as they continue to perpetuate the belief that there are secrets to weight loss. There are no secrets to weight loss. Eat fewer calories than you burn. It doesn't matter if that involves keto, or vegan, or one meal a day. Thyroid problems also don't change physics.

The problem is made worse because overweight people typically greatly underestimate how much they eat, while underweight people (me most of my life) typically greatly overestimate how much we eat. It's nearly impossible to accurately gauge calorie intake without strict calorie counting.

When talking nutrition with people, I'll often bring up the examine.com piece on "does metabolism vary between two people?"(1) And I am always amazed to find at least one person in any conversation that will flat out deny the information presented there. they are positive that if they ate one single slice of pizza a day and nothing else, they would still be fat.

1: https://examine.com/nutrition/does-metabolism-vary-between-t...


> There are no secrets to weight loss. Eat fewer calories than you burn. It doesn't matter if that involves keto, or vegan, or one meal a day. Thyroid problems also don't change physics.

That's like saying "There are no secrets to space flight: For every action, there is an equal and opposite reaction. It doesn't matter if that involves Hydrogen, Hydrazine, or just big tubs of water -- throw them one way, and you'll move the opposite. Your choice of fuel doesn't change physics."

Of course fundamental physics laws hold. But some fuels and systems of using those fuels are more effective than others.

When it comes to diet, different foods and eating patterns do have different effects on our endocrine system, and that does affect how viably we can sustain ourselves on less calories. Different foods will also have different proportions that are retained vs passed the same day.

Unless you also capture ALL your own human waste, and measure it in a 'bomb calorimeter', counting calories (intake only) is not nearly as useful as you seem to think. If you disagree, drink 2000 calories of olive oil every day and eat nothing else, then come back after a year and tell me that calories are all that matter :) Disclaimer: Don't actually do that, because you would starve to death.


I always see this response in these threads and get a little frustrated. I feel like it purposefully misses the forest for the trees a bit.

Sure, at a super granular level, different foods affect you differently, trigger different biological responses, etc.. etc.. but if you zoom out, the details just don't matter. If you're under calories, the weight will come off.

Nobody is suggesting to "drink olive oil." you can keep you normal diet, just eat less of it, and magic will happen.


If you eat a 16 to 20 oz ribeye (1200 calories) in the morning you won't want to eat until at least dinner time. If you eat 3 donuts (1200 calories), you'll be ravenous by noon. What you eat effects when you want to eat and how much dramatically. Why run against a headwind?

Oh boy, I regret commenting in this thread.

I feel like people keep either inventing things to argue against (olive oil) or bringing up scenarios that are purposefully missing the overall point of what people are actually saying.

Again, sure, if you zoom in, eating donuts is probably a bad strategy because you'll be hungry again, and thus eat more calories. But in the grand scheme of things, you CAN eat a donut if you remain below you calories. That is all people are saying. Nothing more. Nothing less.

fwiw, we weight lifters regularly put this into practice. Bulking? add more food. Cutting? less food.

Yes, there are details (gotta hit those macros!), but overall, the strategy boils down to calories in/out.


This is basically the equivalent of the "why does it matter what programming language you pick as long as it's Turing complete, which means you can do anything with it" argument. Losing weight by eating a donut and starving yourself is like writing a web application in brainfuck.

Not at all. It's like saying "it doesn't matter what programming language you pick, the computer is still only going to execute the code you told it to".

Neither the GP, nor the original root of this thread are proposing that food choices are automatic, obvious, or don't have bearing on your weight/happiness/whatever; they're saying that food quantities (in calories) are the primary determinant of how much you weigh.

That's it. Narrow ruling, specific point; no "why don't you just"-ism or anything of the sort--or if it's there, I'm not seeing it.


OK, OK, you're just better than us mere humans. We still experience hunger. And we don't like it. And being dumb animals, our behavior is influenced by that.

You say that like measuring calories in/out is an easy thing to do :-) For most people it absolutely is not, on either end of that.

Case in point: I’ve not met a single person who (in addition to measuring calorie intake) captures all the content deposited in their toilet, and measures it all every day in a bomb calorimeter :)

You off-gas a lot of carbon when you exhale, so it's not a fair comparison.

I've found my body feels hungry simply based on when its used to eating, not what I've eaten earlier in the day. So if I eat breakfast every day, I start feeling hungry at breakfast time, if I eat lunch every day I start feeling hungry at lunch time. Prior food consumption doesn't matter, at least in my case.

I never ate breakfast as a kid, so I carried that habit into adulthood. I started eating breakfast once in a while at some point and that caused me to start feeling hungry in the morning. I shut that shit down right away, I don't need to add more food to my diet. Years later I gave up lunch, which I thought would be really difficult, since I always felt hungry at lunch time, but now I don't feel hungry at all during lunch time, because I'm used to not eating lunch.

YMMV, of course, that just has been my experience.


As somebody who has eaten three normal-sized donuts in the morning (even early morning) a few times, I can tell you I've never been ravenous by noon, or even hungry. Maybe I'd start getting hungry around 3 or 4, which proves your point some, but certainly not by noon.

The question is how you eat fewer calories.

Eating fewer calories is a function of two things:

1. Reducing the number of points in the day in which you eat. 2. Changing the kind of food you eat at each of those points. 3. Changing the quantity of food you eat at each of those points.

From the amount of emotional energy or willpower necessary to do that, it seems like an intermittent fasting regimen is a technique that helps people do that.


>Sure, at a super granular level, different foods affect you differently, trigger different biological responses, etc.. etc.. but if you zoom out, the details just don't matter. If you're under calories, the weight will come off.

Not true at all.

A gallon of gasoline has over 30,000 calories, yet you won't gain weight from drinking it,


This is kind of exhibit A of willfully missing the point...

[deleted]

People had stable weight without any special knowledge for most of human history. It's something we generally should know how to do automatically. It's very strange to compare it to spaceflight, as if we're only just now discovering how to do it. This just goes back to OP's point. There's a lot of energy being spent on making weight gain and loss be some mysterious, inscrutable thing. Now we're comparing it to space flight?

The human body as a machine is actually quite a lot more complex than any current human invention. We're not even close to fully understanding everything. So, the analogy to space flight serves to show that it's as naive to imply there's no subtlety beyond "it doesn't matter what you eat, just the calorie count" as it would be to imply "it doesn't matter what rocket fuel you use".

> People had stable weight without any special knowledge for most of human history.

A lot of food products highly available today would be rather foreign to most of human history: artificially high sugar, high cab, low fat, snacks everywhere, etc.

These trick our taste and hunger systems into eating more of less quality foods than we would "naturally" if exposed only to less "engineered" foods, like pure meat and vegetables.

> It's something we generally should know how to do automatically.

Maybe we should, but clearly we do not. At least with modern processed foods that are optimized and designed to maximally stimulate our flavor response while compromising nutrition/health (generally).


People, especially kids, have routinely died of hunger and gastrointestinal diseases for most of history. Availability of calories was the limiting factor on human numbers until the industrial revolution. Most people did manual labour of some sort and walked everywhere. And when a few people had enough status to get all the calories they wanted and didn't exercise .. they got fat.

Really the problem goes in the other direction: now we have food from the "space age", and labour-saving automation, we can accidentally eat far more calories than we need.


Yes, you are right. And humans commonly engaged in a feasting/fasting cycle of having too much/too little food. But we've pretty much stopped doing the fasting stage. Look up "autophagy". It's a beneficial bodily process that only seems to happen within a long-enough fast.

I believe research has shown that humans have been malnourished throughout most of human history, which would indicate that we haven’t had a stable weight throughout history.

No you wouldn't starve to death. If you didn't take a decent multivitamin you might develop life-threatening nutrient deficiencies, yes.

Also it's not as if we have a great understanding of how different foods influence our food consumption patterns.

I totally agree with ops point. Almost anytime the topic of nutrition comes up people are either unaware of the basic mechanics or have been convinced they're somehow fake [0].

[0] as in that there are huge differences in metabolic efficiency between foods or that people's BMRs usually differ greatly.


You and the other poster are disagreeing before removing significant ambiguity in your claims.

If someone eats 2k of olive oil by drinking one teaspoon every 30 minutes, their body will be able to digest a significant portion of those calories.

If someone drinks the whole cup at once, then they're going to have diarrhea without absorbing much at all.


> No you wouldn't starve to death. If you didn't take a decent multivitamin you might develop life-threatening nutrient deficiencies, yes.

You're claiming that a human can viably survive their whole life by consuming a daily diet of:

    1. Olive Oil
    2. Multi-Vitimin
    3. Water
This seems extremely far-fetched. Do you have a source for this claim?

Semi-related study from the 60s. Guy lived on water and multi-vitamins while his fat stores did their thing: provide energy.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2495396/pdf/pos...


I'm so confused why people are posting this. I agree fasting is viable until you run out of fat reserves (that's what this study is showing).

My point was that the type of food your calories consist of does matter. If you do nothing but drink olive oil and multivitamins, you will lose a lot of weight and eventually starve to death, no matter how many calories you consume. The point is that the type of food you eat does matter to weight gain/loss (not only the calorie count), because the type of food affects how many of those calories you actually retain.

As far as I can see, this study provides no evidence (nor attempts to) that a diet consisting of nothing but olive oil can sustain your weight. I think it's quite well accepted that different kinds of food will be retained to differing degrees in your body (or put another way, different types of food will end up being passed through your system in differing percentages -- as well as with differing degrees of nutritional satisfaction per calorie ingested).


Human fat is substantially more complex than olive oil. Also he survived on more than his fat. He also survived on his skin, some muscle tissue, organ tissues, etc. Research shows increased autophagy during fasts like the one described at your link. During a fast whole organ systems shrink as old senescent cells are destroyed and their nutrients recycled.

The oddest thing about reading the comments here is that people are dismissing the words of someone who has spent the better part of a decade in formal education in medicine, and a large part of his professional career focusing on weight management.


Specifically olive oil might be tough, but I hope a year-long fast will convince you: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2495396/pdf/pos...

The subject in that study lost 276 pounds over the year! If anything, doesn't that confirm what I'm claiming?

I'm not sure how you think this corroborates your claim that you can sustain your weight by drinking olive oil and water (+ multivitamin). In fact, I don't see anything remotely relevant to this in the study.


Not sure what you mean? If he were to eat that well calculated amount of olive oil everyday his weight would stay constant.

I think we're misunderstanding each other. What I don't get is where you're getting the evidence for this claim:

> If he were to eat that well calculated amount of olive oil everyday his weight would stay constant.

A source for this is needed. The study you provided, as far as I can see, says nothing of this. You're just assuming it's true, and I don't understand how/why.


That a gram of fat is roughly 9 calories? You seem to believe that at some amount of regular ingestion it will start getting processed differently? I'm not sure what kind of a paper you'd like, I don't think anyone will come up with specifically olive oil.

As per your other reply to the same link

  differing degrees of nutritional satisfaction per calorie ingested
Yes it's commonly thought to work that way, there are indeed differences - but they're tiny. I might try to dig up relevant papers, but as far as my memory goes, the difference was at best around 3% with certain kind of protein.

Nah pretty sure that'd just give you massive diarrhea.

Wow! Interesting paper. It appears to be saying that he went over a year without any "essential" amino acid intake. I would not have thought that possible.

> I'm so confused why people are posting this.

Replying here because I can't reply to where you posted this ^^

Everyone's posting it because you are wrong. A calorie is a calorie. If I eat 500 calories surplus a day, i'll gain ~1 pound a week.


> If I eat 500 calories surplus a day, i'll gain ~1 pound a week.

Not if you expel an excess 500 calories per day on the toilet. This is what would happen if you chug a glass of olive oil, for example -- your body won't digest it all, and the vast majority of it will pass straight through.

This is an extreme example, but I make it to demonstrate a point 'calorie couters' always seem to forget: You keep assuming that you retain 100% of the calories you ingest, minus what you burn. This is demonstrably incorrect.


Would some qualifiers help?

Like, "calorie count is the primary determinant of weight gain, given nearly all typical human eating habits"?

Or "calorie count is the primary determinant of weight gain assuming you don't deliberately bypass your digestive system (likely inflicting discomfort and/or harm on yourself in the process) by consuming diuretics or indigestible food combinations"?

Even in both of those cases, it seems like the general point is still pretty much intact.


>Everyone's posting it because you are wrong. A calorie is a calorie. If I eat 500 calories surplus a day, i'll gain ~1 pound a week.

Bullshit. A calorie is an incredibly crude metric of energy when it comes to human metabolisms. Our stomachs are not furnaces.

Try eating 500 calories surplus of gasoline or wood.


> When it comes to diet, different foods and eating patterns do have different effects on our endocrine system, and that does affect how viably we can sustain ourselves on less calories. Different foods will also have different proportions that are retained vs passed the same day.

People who care about this aren't interested in the secrets of the endocrine system. They are interested in how they can remain trim while eating rich food like meat and dairy. These folks like fasting because they can eat one large meal and get more stimulation from the food.


The premise you've presented fascinates me. I wonder what would be the impacts of a 2000 calorie olive oil diet. Is it truly a starvation diet (due to inability of the body to process those calories)? I generally agree with the "calories in, calories out" principles of weight management, but I could see this being a useful counterexample.

If you break it down into carbs, fats and protein, calorie in calorie out model does wonders. OP is right, weight loss is hard work. Frankly, people want to believe that there is an alternate method because a lot of them are just lazy.

Also, it's easier to maintain weight than to loose/gain weight. So once you have lost that weight, it's much easier to be at that weight. Of course you lost a huge amount of weight in a short span, this won't be true.


For the majority, losing weight is not tough in theory. In practice, however, will-power causes most trouble. It is really easy.

Species-specific diet can do wonders in a very short time. I have tried it with my dogs and I am trying this on myself. I am seeing excellent results.


This comment has very little to do with the comment above it, which makes the point that weight is dictated by net calories, with very few exceptions.

The calories in/out model is technically true, it's just not very useful. It's like saying "there's no secret to how a jet plane works, you just need to have enough lift to counter gravity, it's basic physics." Well, sure, but there are a lot of other variables to consider that will dictate how hard/expensive it is to build a working aircraft.

Playing with other variables besides calories, like the specific foods you pick and the timing of meals, can produce dramatic, measurable health changes and make a huge difference in how hungry you will feel at different times of day.

EDIT: I just saw the other reply someone wrote that used a rocket analogy instead of a jet plane analogy, funny how we both independently came up with such a similar response.


> Playing with other variables besides calories, like the specific foods you pick and the timing of meals, can produce dramatic, measurable health changes and make a huge difference in how hungry you will feel at different times of day.

It is true that the kinds of foods you eat may help you with maintaining a caloric deficit -- for example, eating high-volume foods such as vegetables, or low-GI whole-grain carbs may help you feel "full" longer than low-volume foods with high caloric densities (candy, snacks, sodas). But the most important thing is still calories. See a recent meta-analysis on this: https://jissn.biomedcentral.com/articles/10.1186/s12970-017-...

Also, timing of meals is actually not that important for weight loss. It is somewhat important for sports performance (e.g., timing carb intake around sports activities). There was a meta-analysis a few years ago that gave more specific recommendations: https://jissn.biomedcentral.com/articles/10.1186/s12970-017-...


> The calories in/out model is technically true, it's just not very useful.

It's plenty useful. The biggest barrier I've seen so far in people trying to lose weight is that they just plain don't believe it, and think it won't work. They think they need some complicated specially tailored diet where they need to pick out specific foods, eat foods they don't like, eat at special intervals, and so on.

> Playing with other variables besides calories, like the specific foods you pick and the timing of meals, can produce dramatic, measurable health changes and make a huge difference in how hungry you will feel at different times of day.

That may be true, but various tricks you might choose to apply to your diet should come /after/ you know how many calories you're consuming. It's a question of where your attention is directed. The purpose is still to reduce calories, and preventing hunger in whatever way works for you or distracting yourself or maintaining a schedule are all just means to the same end: to reduce how much you're consuming.

The problem I see is that people seem to not agree on that /end/ and think they're trying to accomplish something else, but I'm not sure how that's supposed to be measurable or reliable.


I disagree with that end. The purpose is not to reduce calories, the point is to be, feel, and look better. Counting calories is tedious and inaccurate. "Don't eat outside of X window" is much less effort, and anecdotally, has given me better results.

I don't need to know my calories at all, my metabolic system can be a complete black box, and as long as I'm able to do stuff I enjoy without feeling groggy, eat almost whatever I want, and just sacrifice the timing, I'm happy.


> Playing with other variables besides calories, like the specific foods you pick and the timing of meals, can produce dramatic, measurable health changes and make a huge difference in how hungry you will feel at different times of day.

Exactly. Try to stay under your daily calorie quota eating just processed carbs/sugar and you're gonna have a bad time. Will you still lose weight? Sure, if you can actually withstand feeling hungry constantly. Compare that to the same # of calories from veggies and fat and most people will tend to feel much more satisfied overall. I've been doing keto for 12 weeks along with intermittent fasting and this has been the case for me. I can easily get a sizable daily calorie deficit without really trying and rarely feel hungry.


> There are no secrets to weight loss. Eat fewer calories than you burn. It doesn't matter if that involves keto, or vegan, or one meal a day. Thyroid problems also don't change physics.

You seem focused on the physics and materialist viewpoint, but it seems like you are taking that line of reasoning just far enough where we can be judgmental and snarky about "secrets."

What if we take your thinking a little farther and think about the brain chemistry and drives that affect behavior. We are just materialistic machines, right?

Ever seen a sick person who just doesn't want to eat? Or a skinny person with little interest in food? Ever try to hold your breath for 3 minutes? This should, in theory, for the average person be possible. But for some reason it is really really hard.

What if, these diets don't affect the physics of weight loss, they affect the hunger drive--the chemicals in the brain? Do we still get to ride our moral high-horse then?

Or what if there are drives and chemicals in the brain and even the metabolism itself fights back.

https://www.scientificamerican.com/article/6-years-after-the...


Excellent points

> Or a skinny person with little interest in food?

And yes, that's me all the time.

What i'm saying is, everyone has a resting metabolic rate. That rate is relatively stable among the entire human population. If you eat more than your metabolic rate, you gain weight. Less, and you lose weight.

Most readers on hacker news are saying "duh ngngngng, but you're oversimplifying". Correct, I am. But the reason for that is I believe most Americans (maybe other countries too), do not believe the information I just presented. Most Americans think if they are fat that their resting metabolic rate must be 1500 calories different from most skinny people.

I think this creates a sense of hopelessness. "No matter what I eat, i'll be fat. But no matter what ngngngng eats, he stays skinny!" Even though the reality is my metabolism is average, and the referenced overweight person probably has a similar metabolism as me.


Sorry, but you're not helping. There is not a lack of people, media, and doctors who repeat the calories in calories out mantra. People have this hammered into them all the time. And it's obviously not working.

"No matter what I eat, i'll be fat. But no matter what ngngngng eats, he stays skinny!"

This is plain denial, and is not the view expressed in the article. Anyone who reads and understands the article, and the purported benefits isn't likely to simultaneously hold that inane view.


> What i'm saying is, everyone has a resting metabolic rate. That rate is relatively stable among the entire human population.

You are probably confusing BMR and RMR; Basal Metabolic Rate is a reasonably constant function of age, weight, body composition, and gender for healthy, non-pregnant adults.

RMR varies considerably even for an individual based on a wide range of factors, including emotional state.

> Most Americans think if they are fat that their resting metabolic rate must be 1500 calories different from most skinny people.

And they are quite possibly right; fitness lowers RMR with the same BMR, and a 300 lb 6’0” man has a ~900 kcal higher BMR than a 150 lb man of the same height under te adultos used in simple BMR calculators. And there are a number of other ways that being overweight contributes to or is correlated with factors than contribute to different RMR (and in some cases BMR).


Telling people to eat fewer calories than they burn is useless without telling them how.

As you yourself acknowledge, it’s not that simple. You use calorie counting to stay on track — but that’s another secret to weight loss, isn’t it? You may not think of it that way because it works for you (which is great by the way), but that’s what it is.

But now we’re getting to the meat of the issue. Eating fewer calories than you burn results in weight loss, but how? We should be focusing on the methods that work for many people. If we know what they are, we can advise people attempting to lose weight to try them and hopefully most wont have to try too many before they find one that works for them.

As far as I can tell, the three methonds that work well for many people are: (1) strict calorie counting (usually app + food scale), (2) intermittent fasting — which is what this article is about — and (3) keto.

Of course, it’s fair to scoff at and criticize the methods that usually don’t work well especially when results are oversold especially in money-making schemes. But this guy is just promoting IF in a fair and reasonable way.

Also, there is a reasonable chance IF has health benefits beyond weight loss, which is potentially a reason to prefer it over calorie counting (although I found that when calorie counting I was effectively doing a mild IF anyway)


> The problem is made worse because overweight people typically greatly underestimate how much they eat, while underweight people (me most of my life) typically greatly overestimate how much we eat. It's nearly impossible to accurately gauge calorie intake without strict calorie counting.

This suggests that you might be able to take pairs of people, one who is overweight and one who is underweight, and help both of them by simply arranging for them to eat every meal together and do all their snacking together.

For each meal or snack, each buys or prepares what they normally would, but before they actually consume the food, they each exchange half of their food with the other.

There...an easy to follow diet, without strict calorie counting, that should move the overweight person to a lower weight and put some weight on the underweight person.

You could probably build a reality TV show around this. Half the contestants would be people wanting to lose weight, and half would be people trying to gain, with the lowest weight person in the first group being substantially heavier than the highest weight person in the second group.

Each week, there would be challenges and contests which determine priority for picking who your eating partner will be for the next week.

Pick the contestants from a wide range of culinary cultures and ethnic and religious backgrounds so that some potential pairings would be difficult for the participants, and so doing well in the challenges is important.


I've actually had this idea for years. When I was a teenager, I was constantly told by classmates or family members, "I wish I was like you and could eat anything I want and stay so skinny!"

I didn't understand the information in my original comment at the time, but it occurred to me it might make a fun documentary to have me live with someone morbidly obese for a month and eat everything they eat when they eat it and see if I gained weight.


Unfortunately the human body is quite a bit more complicated than that and a single article on examine.com is woefully inadequate at capturing the complexities. While people's metabolism doesn't seem to vary too much from person to person, it does tend to vary a lot within the same individual based on lifestyle choices. Whether I choose to eat or not, or choose how much to eat, my metabolism can vary.

When you consider your glycogen reserves, carb vs fat metabolism, insulin, ghrelin and other hormones, you get a rather complex machine. And what's really frustrating is that you are technically correct, in a sense. Eat fewer calories than you burn and you will lose weight. But that simplification borders on the dangerous. What's missing is that your body is not some passive observer, but an active participant, trying its best to help you survive.

Your body is amazingly good at adjusting how much you burn. When you cut calories, say 500 a day, your body will tend to compensate by burning a little less by reducing its temperature, by reducing fidgeting, by reducing your mood even! You'd need to cut 500 calories ABOVE that difference. So you end up having to cut closer to 750-1000 calories per day to get the same effect. Whereas when you fast, your metabolism rather obnoxiously tends to rise.

It ends up being healthier (and much easier) to eat 3500 calories less in one go, rather than splitting the difference across 7 days.


I don't think many people believe there are "secrets" involved, but there are many factors which make sticking to a diet easier for people.

The linked page talks about this quite a bit - Trying to control for hunger, fullness, desire to eat, etc.

"This was a randomized crossover, isocaloric and eucaloric study. That is, all patients did both arms of the study eating the same foods and the same calories and then compared against themselves. ... Those who restricted late-night eating had less desire to eat, but also less capacity to eat. They couldn’t eat more at night even if they wanted to. That’s amazing, because now we are working with our body to lose weight instead of constantly fighting it. "

Respectfully, I'm not really sure I understand how your critique applies to this article?


There are no secrets to weight loss. Eat fewer calories than you burn. It doesn't matter if that involves keto, or vegan, or one meal a day. Thyroid problems also don't change physics.

The point of the article is, the timing of feeding vs fasting leads to differences in fat storage.

The work of Dr Fung, among others, suggests that concentrating eating into a few (4-8) hour period per day causes better outcomes than feeding during the entire waking period.

Same thing with the balance of macronutrients. Tuning the ratio of fat:protein:carbohydrate can make a diet more filling and more sustainable on fewer calories. This enables that "calories in / calories out" rule to actually work and cause reduction in stored body fat.


> It's nearly impossible to accurately gauge calorie intake without strict calorie counting.

Yes, but you can get most of the way there just by counting for a while, so that you build a model in your head for how many calories different foods have. Unless you've counted before, the results can be surprising. Stopping at Starbucks for a snack and deciding between a cake pop [0] and the chocolate chip cookie [1]? The cookie has 380 more calories.

Thinking about grabbing a quick lunch and trying to decide between a burger from Shake Shack or a burrito at Chipotle? That burrito could easily have 1200+ calories [2]. The burger has 530. [3] (A bowl without rice at Chipotle, on the other hand, can have as few calories as the burger. So, again, knowing that difference can help you make better choices.)

These are just random examples from my own life, recently. Knowing these differences makes a difference (especially over the course of many meals).

[0] https://www.starbucks.com/menu/food/bakery/cat-cake-pop?food...

[1] https://www.starbucks.com/menu/food/bakery/chocolate-chip-co...

[2] https://www.chipotle.com/nutrition-calculator

[3] https://www.shakeshack.com/food-and-drink/


That article doesn't disagree with what you're saying. My two takeaways were:

1) We snack more now than we did 50 years ago and those extra calories are probably why we're fat.

2) Reducing the window of time that you eat during the day reduces your desire to eat and your ability to consume.

I'm not sure how you took that as perpetuating a secret to weight loss.


Of course things are not so simple. Calories in/calories out partially applies to weight gain/weight loss, but it's not the complete story. Hormones also play a role.

That's why people start to gain weight as they grow old, even though they eat the same. It involves testosterone/estrogen and an enzyme called lipoprotein lipase.


> It involves testosterone/estrogen and an enzyme called lipoprotein lipase.

This is just a variation of the thyroid problem reasoning. Hormone changes with age or thyroid issues might change your resting metabolic rate over time by 100-200 calories per day (a single candy bar of calories). But that doesn't curse you to be fat, which is what I am trying to disprove. You will then need to adjust your intake/exercise level accordingly to the new resting metabolic rate.


I didn't say that hormone changes lower your resting metabolic rate. They simply make your body be more inclined to store fat. The enzyme that I mentioned LPL, becomes more active and stores more fat.

Have you ever wondered why men and women tend to put on weight differently? The same enzyme is involved. For men it's more active around the waist. For women, around the thighs.

For a thorough treatment of this topic, I recommend the book Why We Get Fat by Gary Taubes. It goes into the biology of why we get fat. Note that it's pretty strong against carbs, so depending on your beliefs, you might not like it. Although, I have to say, it makes a pretty convincing case on why we should lower carbs intake.


> There are no secrets to weight loss. Eat fewer calories than you burn. It doesn't matter if that involves keto, or vegan, or one meal a day. Thyroid problems also don't change physics.

Unfortunately that is not true. Different foods are metabolised differently. It is not just "calories in, calories out".


It's like saying there are no secrets to computing and to just imagine a computer as a Turing machine, forget about stuff like pipelining and caches and whatever. On the other hand, I do believe the supposed "secrets" have actually been known for a long time. Here's my favorite article about it: http://www.grubstreet.com/2018/03/ultimate-conversation-on-h...

Damn, this thread is full of actual good analogies today! Thanks for this one :)

There are plenty of ways to optimize fat burning/weight loss beyond eating fewer calories. When you eat matters. Working out in a fasted state will accelerate fat burner vs working out after eating a meal. Eating a similar number of calories in a keto diet vs a carb-heavy one while maintaining a calorie-deficit will also accelerate fat burning/weight loss.

Calories in/calories out is a simple pipe dream that conveniently ignores the deleterious effects that hormones can have on your metabolism.

There are tons of people out there intaking less calories than their BMR and not losing weight because they have thyroid issues, are insulin resistant, etc.


There's way more to this story as people are pointing out.

I talk about a lot of this stuff with nutrition experts on my podcast http://peak-human.com and am getting the author of this article on soon.


There are other benefits beside weight loss. Changing the way you eat seems to be linked to a lot of part of your system.

Ketosis reduces your appetite substantially.

Totally. I'm not convinced that keto is any more efficient at burning fat, but eating my normal meat-starch-vegetable meals without the starches probably cuts 1000 calories per day out, so there's the calorie restriction. The magic comes in where I'm not ready to gnaw my arm off or murderously hangry on that amount of calories, versus trying to just eat less of the full blend.

Insulin will cause your body to store more fat and is released when you intake carbohydrates.

Macro content does matter and not all calories are created equal.

Calories are actually an incredibly crude measurement of metabolism energy, as our stomachs are not furnaces. Gasoline and wood have tons of calories, but no usable energy for humans.


Maybe? It definitely hasn't been shown to be any more effective than a fat free diet.

I mean appetite isn't really quantifiable anyway. Sure you can look at leptin and grelin, one of which actually is greatly affected by fasting.

Less hunger, less calories.


As others mentioned there’s an aspect of efficiency there but I think there’s something more important.

The whole discussion revolves around losing weight while diet and nutrition is not really about that. It’s about how to eat to stay healthy. Not being obese is just a part of that.

If you consider the bigger scope you’ll realize that despite the fact it came out from Neil deGrasse Tyson mouth, in this context it’s just a stupid thing to say.


If I eat 5 burgers a day and reduce it to 2 a day, I will lose weight. However, no amount of burgers is good.

For more than a decade I had been fasting intermittently. I ate one very huge meal everyday. Typical Indian meal with fair bit of non-veg included. I was not in the best health possible.

A year ago, I got rid of non-veg from my diet. Things improved a bit, but I wanted better results. One month ago, I went fully raw - only raw fruits and no vegetables. I lost many pounds and everybody notices, my sinus troubles have vanished, I feel and look good overall.

I eat more than ever, but am losing weight.


> If I eat 5 burgers a day and reduce it to 2 a day, I will lose weight. However, no amount of burgers is good.

What's so terrible about burgers? From what I can see they're much less harmful than just obesity in and of itself.


Burgers are terrible food. They are addictive and are loaded with empty calories.

Edit:

Downvoting me will not change facts.


Burgers have between 20-40 grams of protein, from optimal sources of protein (i.e., beef). A serving or two of vegetables in the form of lettuce, tomatoes, and onions. Maybe vitamin D if mushrooms are included. Fiber, in the form of bread, and possible trace vitamins and minerals if using wheat bread.

Doesn't sound at all like empty calories to me. Considering that most raw vegetables have poor bioavailability (so most of the nutrients you eat from raw foods don't get absorbed), I would posit that a good burger is healthier than 90% of raw food meals...And moreover, than you could simply add the raw food to a burger to make it instantly superior to any equivalent raw food meal of the same weight/mass or calorie count.


Bread is bad. Refined wheat flour baked; full of acrylamide. Beef is as bad. And what about all the cheese? Vegetables are better, but still not the best as far as human digestive system is concerned.

Look around you. If these things were so healthy, why is the population getting sicker by the day?


If you're just going to spread unsupported lies, I'm not going to keep this conversation going. People have been eating meat, bread, and vegetables for thousands of years without issue. If any of these were the problem, the human race would be dead by now.

Hell, the Eskimos ate a diet almost entirely meat-based for hundreds of years. It wasn't until they were introduced to fruits that they began developing diseases like diabetes. Steve Jobs' health nose-dived once he switch to the fruitarian diet; research now shows that the fructose and glucose in fruits is in fact the number one preferred fuel source for cancer cells, which is why the current dietary advice is for cancer patients to go on low carb or ketogenic diets.

The greatest athletes in history eat omnivorous diets; during his record-setting Olympics run, Michael Phelps ate thousands of calories of fast food each day. Few professional athletes are vegetarians, and no elite athletes are fruitarians. All of our most famous scientists, including Einstein and Hawking, ate balanced diets that included substantial amounts of meat. The evidence, and thousands of years of human history, speaks for itself.


> People have been eating meat, bread, and vegetables for thousands of years without issue. If any of these were the problem, the human race would be dead by now.

People have been smoking for thousands of years. Smoking causes cancer was proved just 50-60 years ago. Is our species dead? Baked, fried, grilled food have heavy amounts of acrylamide, a carcinogen. Read the Swedish study.

> Eskimos ate a diet almost entirely meat-based for hundreds of years

This is a myth. Do some research.

> research now shows that the fructose and glucose in fruits is in fact the number one preferred fuel source for cancer cells

If one already has cancer, sure. They are the preferred fuel source for all cells because they are so easy to process. Cancer cells too use them. Credit cards are great for us, fraudsters too like them...

Research shows everything except the root-cause and cure for cancer.

> Michael Phelps ate thousands of calories of fast food each day.

That is moronic in the long-term. Short-term benefits of steroids in muscle-building are well documented too.

> Few professional athletes are vegetarians, and no elite athletes are fruitarians

Indian wrestlers are vegetarians. Some of them world famous. You are absolutely wrong.

> All of our most famous scientists, including Einstein and Hawking, ate balanced diets that included substantial amounts of meat.

Ramanujan, one of the greatest Mathematicians, was a vegetarian. So are most Indian Brahmin scientists and mathematicians of today and of all eras. You are absolutely wrong.


You're still not explaining what specifically is unhealthy in a burger.

The only thing I can think of is the bun which can be replaced with a lettuce wrap or salad bed.


Only eat raw vegetables and you'll lose even more. Reason: they're mostly water anyway and less sugary that fruits, so less carbs. You can fill your belly with them and you'll get very little calories.

Another possibility: only eat naturally blue foods. Or only eat foods beginning by 'K' (a different one each day of the week).


I don’t eat anything that casts a shadow.

Bulletproof diet.

This is known as the "Steve Jobs" diet plan

I do not think so. Mahavira (Jainism), Buddha and countless other saints have preached the benefits of such diets for thousands of years in India.

Your claim and your supporting argument do not align. Fruitarianism can have been preached about for thousands of years and also be the diet associated with Steve Jobs.

Who came first? Why do we need to assign a Western figure to a method preached by eastern philosophers?
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