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Fasting improves chemotherapy results and protects from side effects: study (nature.com)
355 points by alz 4 days ago | hide | past | favorite | 208 comments

Interesting study with, as always, a lot of caveats. The most we can take from this is that it's worth to study more, the effect is existing but not extreme.

I don't get the submitted title here claiming that it protects from side effects. The study does not mention this at all, just that the side effects are similar despite omission of dexamethason in the fasting arm of the trial - it increases appetite, so makes sense to omit it if you want any reasonable compliance rate.

As with any fasting and dieting study, compliance is moderate at best. In this study, only 33% of patients were compliant for at least 4 cycles of chemotherapy, out of 12 cycles total. Most of them were compliant with at least once cycle though.

Overall, we need some more research on this in a larger trial. This paper is a call for funders to do just that - the trial ended prematurely due to needing to include more patients but there was a lack of funding to do so.

I'm currently doing research on a similar patient population, so open to answer any questions.

I'm not convinced the 2/3 dropout rate of the FMD didn't simply select for people with less aggressive tumors, given that the Intention-To-Treat analysis found no difference in response rate, and that this paper is telling a nice story that actually happens to reverse cause and effect.

Basically, this?


Since you're researcher in this field and I'm just a weirdo who likes watching scientists argue on Twitter, I'll ask: Anything you can see in the paper that would give a clearer picture regarding possible bias that might have snuck in?

That could very well be a possibility and something that researchers need to address if they wish to investigate this effect a bit further. We can make some educated guesses based on the supplemental table 3. Looking at the staging, grading, tumortype and the hormone receptor status, there don't seem to be any significant differences between the compliant and non-compliant groups. We know that those are the most important factors in assessing how aggressive a breast tumor is, with distinct treatment options and overall survival. So based on this information, I'm inclined to say the cause/effect is not reversed.

Of course, there could be some factors determining aggressiveness and response to chemotherapy that we do not know yet. Unfortunately I'm not in regular patient contact so can't say a whole lot about typical side effect profiles of chemotherapy, but I've heard some anecdotal evidence that for patients treated with immunotherapy, the more severe the side effects, the better the response.

Thanks for clarifying comments here, much appreciated.

I have to think my initial comment was overly harsh as well, given Supplement 3.

I think all I can say is that it may be possible for this issue to affect their data once they have OS stats accumulated in five years, but it was unlikely to do anything to yield differences in adherence with these kinds of patients over this kind of follow-up length.

"The main reason for non-adherence to the FMD was dislike of distinct components of the diet, perhaps induced by chemotherapy [...] The FMD is a 4-day plant-based low amino-acid substitution diet, consisting of soups, broths, liquids and tea"

Occam's razor, patients couldn't stick with the diet.

I started fasting every Monday for multiple reasons: reduce caloric intake, the recent studies on reduction of cancer growth (family history cancer and heart issues), and optimizing brain functions.

What are some of the downsides to doing this?

Hello! Long time faster here (lost over 80lbs in about 9 months with basically zero exercise).

One potential downside to steady regimented fasting _when combined_ with caloric restriction, is a decrease in your basal metabolic rate (BMR).

Our bodies are very good at adapting to "the new normal" and will optimize itself to function on the fuel you give it. This is true in both directions. If you eat less, your body will learn to live on less, and if you eat more, eventually your body will ramp up to try and burn more energy to try and reach an equilibrium.

When fasting, it's important to keep your caloric intake up during brief eating windows. Otherwise, your body will adjust, and when you stop fasting, the slightly increased caloric intake will cause you to gain weight before your body readjusts to the new normal. Many fasting theorists suggest that fasting at random intervals is the best strategy for weight loss without reducing BMR. If your body is used to burning 3000 calories a day just to keep you alive, it can't ramp down those cells immediately so it needs to instead convert stored fat to energy and burn that instead.

These aren't fasting specific, but oftentimes in the western world, we begin fasting as a means to an end (weight loss) and often combine it with other dietary changes, like eating less/healthier.

The other downside is literal starvation or the development of an eating disorder, but those are pretty obvious.

I saw a low-budget documentary on YouTube[0] a couple of weeks ago talking about "fasting retreats" in Russia and now parts of Europe that are seeing great results with patients water fasting for 2+ weeks. They're treating everything from Diabetes to arthritis and dementia. Pretty cool stuff.

Personally, I definitely have seen the light and will likely continue fasting regularly in some form the rest of my life. Since I just turned 26 last month, that's going to be a while! I'm currently half way through a 72 hour fast and feeling great. Just had a cup of coffee and some electrolyte spiked water this morning. I still have about 50 pounds to lose but I'm hopefully for my future now and I'm a lot healthier.

[0] - https://www.youtube.com/watch?v=t1b08X-GvRs

It sounds like we are both doing the same thing but through different means. I have been on a successful low-carb, high-fat diet for around 7 years now and will never go back to eating high-carb foods on a daily basis. I lost 45 pounds in the first 9 months with no exercise and have kept it off since. Although the weight loss was nice, it was not my main goal. I originally changed to a LCHF diet because I was tired of being constantly hungry and having my schedule and life dictated by food.

Fasting is one of the things that a lot of LCHF practitioners eventually gravitate towards because once your metabolism is used to burning fat, you're not hungry all the time and eating becomes optional. I typically eat two meals a day but sometimes one is more than enough.

I have tried fasting here and there but getting better at it is one of my goals. My main difficulty right now is easy access to food (being stuck working from home most days) and the social pressure of being the only one in the house who has committed to LCHF.

Yeah social pressure within your own home is no joke! My SO doesn't eat LCHF, so the fridge and pantry are littered with foods I cannot eat.

One way I've gotten through this recently is to use a pre-packaged meal delivery service. I order 30 meals at a time for $175 and that lasts me a month or so eating 2 per meal, 4-5 days a week. If I'm hungry, my food options are what's in the freezer, or a bag of popcorn.

I've found one of my biggest motivators for fasting is actually the pride I get from discussing it with friends and family. I'm not a prideful person, but it feels freaking great to boast nonchalantly about not having eaten food in a few days. The results also speak for themself as well.

If you don't have a fasting tracker app, I recommend finding one you like and trying to get some others on board. If you're interested, I have a group from posts on my blog that people hop in and out of [0]. Anyone feel free to join and post updates and I'll keep an extra close eye on it for the next few days.

0: https://lifefastingtracker.app.link/z3D7qHg2W8

> One potential downside to steady regimented fasting _when combined_ with caloric restriction, is a decrease in your basal metabolic rate (BMR).

Check out The Complete Guide to Intermittent Fasting. The research he cites shows that the effect you describe occurs in caloric restriction diets, not fasting. Fasting increases HGH and maintains BMR.

Perhaps what you are describing is the early days of fasting when your body is becoming fat adapted and you feel a bit sluggish, but after a short period your energy levels return to normal (for me it was less than a few weeks, 5 years ago, and my wife just started fasting with me and she is adapted and back to full energy while fasting after two weeks).

I've read the book. The same thing still applies and I believe I've seen a video where Fung has confirmed it but I don't have the link handy.

Fasting enables us to not have to focus on calorie restrictions to see a reduction in body weight. However, if you only eat 500 calories a day, eventually you will run out of fat and your BMR will go down as you approach a lower BMI.

It's a very slow and gradual process, but it does happen. If you've got plenty of fat to burn, not a huge issue, but as you lose weight it can start to apply more.

Anecdotal evidence also suggests that people who stick with a very strict IF schedule tend to see slower results and bigger plateaus than those who change things up more often.

Right, I see what you are saying. Your BMR decreases not directly due to fasting but due to the fact that you are a lower weight. The results of fasting (weight loss) leads to lower BMR. Whereas caloric restriction shifts BMR down regardless of whether weight is lost.

I agree with your anecdotal evidence. I do 36 hour fasts 2x per week, and otherwise do 20-22 hour fasts. Every now and then I do a longer, 48-72 hour fast. I am in awe of people that get to 5-10 day fasts and hope to work up to this over time, perhaps on a quarterly basis.

Outside of my Monday all day fast, I typically intermittent fast throughout the week. I am liking the results

I fast regularly and have a 5-6 hour eating window. During that window I just cannot eat more than 1500 calories. If typical caloric reduction can trigger starvation type response in the body, why does it not happen when we reduce calories during fasting?

Caloric restriction does not lead to an increase in Human Growth Hormone. There are a bunch of other hormonal changes that occur when the caloric input is zero, versus when it is something. That’s why study after study shows fasting is superior to caloric restriction.

Thanks @voisin, this is very helpful.

My wife is Stage 3, ++- (43 yo) and half way through the taxol phase of an ACT regimen; she is progressing well but I know she has the discipline to do a fasting diet if we thought it would help. Any thoughts on starting this mid-way through the treatment?

Absolutely not a doctor, so no way qualified to give professional advice, but the article states that not everyone followed the diet during all treatments, so they included all patients who complied at least during half of the cases, and the positive results are based on this extended group. This, and the suggested mechanism of why they think the method works, would lead me to believe that it makes sense to try it.

Wish you & your wife strength and all the best.

Try it. My mom (she left us last year at only 53, unfortunately) and I did intermittent fasting (>=16 hours), and ate a super clean and mainly ovolactovegetarian diet for most of her illness. Her life expectancy was only six months, with breast cancer and methastasis; she endured six years.

Do anything you can to help her be healthy. Diet is of extreme impoortance.

I'm sorry to hear that about your wife and wish her all the best. As I'm not a medical professional and don't know your wife's exact situation, I'd say it'd be best to bring it up with your wife's oncologist that you'd like to give it a shot. I doubt they'd object for trying it for a cycle or two, but they know best.

I'm not a doctor, but after reading Tripping Over the Truth: The Metabolic Theory of Cancer [0] I'd strongly suggest she start fasting, or, far better, order yourself a copy of the book (epubs available for purchase/torrent) and read it, decide for yourself. There are a lot of resources listed in the book for people who have cancer.

I'm trying to get people to read the book. Average people, for sure, but also people on boards of research institutions. I wrote this to one of them: https://josh.works/mike-clayville-can-have-a-huge-impact-on-...

[0] https://www.goodreads.com/book/show/23496164-tripping-over-t...

The ideas contained in the book are explosive, with profound implications. It's a riveting read.

Why is it that as soon as cancer comes up as a topic, people stop exchanging arguments and start selling books instead, where normally they would be paraphrasing and occasionally referencing something.

I left a longer answer to a similar question here: https://news.ycombinator.com/item?id=24260568

A book is nothing but a long, detailed, carefully-researched argument. Or, at least the book I'm recommending is that.

If there are words I can say to convince you to read the book, please tell me them.

I'm literally paying people to read the book.[0]

I would love suggestions on how to improve the average discourse on the topic. What would you suggest?

Could you read through the linked thread, tell me if there's anything there that I should bring over here?

[0]: https://josh.works/mike-clayville-can-have-a-huge-impact-on-...

Not buying from you, not helping you sell for free.

Idk what brought you on your mission, but your pitches interrupt discussions.

"Importantly, DNA damage in T-lymphocytes was less in patients who received the FMD in combination with chemotherapy compared to those receiving chemotherapy while on a regular diet"

Does this not qualify as a protective effect?

You may be right, but the reason I put that in the title was because it begins by siting a bunch of other research evidencing that “short-term fasting ...can protect healthy cells against a wide variety of stressors, including chemotherapy”, because in the trial they were able to omit dexamethasone with no negative effects, and because “chemotherapy-induced DNA damage in T-lymphocytes“ was “significantly curtailed”

Do you have any info as to which fasting schedule is most effective?

Unfortunately that is far outside my expertise. The study here used a diet that is supposed to mimick the effects of fasting by having a low calorie/protein diet. In the discussion, they say the effects on a growth factor can be measured in blood plasma after 48 hours of fasting, or 48 hours of this diet.

My layman guess is that the best schedule is probably the one you can adhere to.

If it's a low protein diet, couldn't the lack of certain aminoacids which promotes cell growth (and by that, also cancer growth) also aid slowing cancer?

Layman here, just popped into my mind.

The explanation in the article is sort of along those lines, if cancer cells' inability to switch to a protective state is due to their faulty programming always keeping them in a growth mode:

"Essentially, fasting causes a switch in healthy cells from a proliferative state towards a maintenance and repair state. Malignant cells, in contrast, seem to be unable to enter this protective state because of oncoprotein activity, and therefore fail to adapt to nutrient scarce conditions. Instead, fasting deprives proliferating cancer cells of nutrients, growth and other factors, which renders them more sensitive to cancer therapy and increases cell death"

Don't cancer cells also require massive amounts of glucose to survive?

I think you are referring to the Warburg effect:


This is what they mean by fasting mimicking diet, and includes the schedule: https://www.cell.com/cell-metabolism/fulltext/S1550-4131(15)...

Why make people search instead of quoting the relevant section?

"The human fasting mimicking diet (FMD) program is a plant-based diet program designed to attain fasting-like effects while providing micronutrient nourishment (vitamins, minerals, etc.) and minimize the burden of fasting. It comprises proprietary vegetable-based soups, energy bars, energy drinks, chip snacks, chamomile flower tea, and a vegetable supplement formula tablet (Table S4). The human FMD diet consists of a 5 day regimen: day 1 of the diet supplies ∼1,090 kcal (10% protein, 56% fat, 34% carbohydrate), days 2–5 are identical in formulation and provide 725 kcal (9% protein, 44% fat, 47% carbohydrate)."

"Subjects in the FMD cohort consumed the provided experimental diet consisting of 3 cycles of 5 continuous days of FMD followed by 25 days of normal food intake."

If there were ever a panacea, it would be fasting. The more tight and widespread the research becomes, the more that we prove what humanity has known anecdotally throughout civilisation.

From being a Roman cure for epileptic seizures, through the integral practice in most religions, and to the 21st century where we start to prove that it increases both healthspan and lifespan.

I find it quite interesting that something so simple, which practically anybody can do, can have such a positive effect on one's life. You are literally healing and regenerating yourself by doing nothing! And instead of compounding medical bills you actually save money!

Thank you modern science for validating my no longer fringe medical beliefs :)

I always find it funny that fasting comes up so often, but a ctrl-f almost never turns up someone mentioning Ramadan. Nearly 25% of the world population fasts for an entire month, but it's almost invisible to the western world. While I don't agree with all of the details of the fast (I drink water), I think it is an admirable holiday, it's way healthier for the world than Christmas or Thanksgiving.

I lived in Saudi Arabia for two years and did Ramadan, out of not wanting to offend my Saudi colleagues who were fasting.

As a practictioner of fasting, I don't think that "modern" Ramadan has much to do with fasting anymore - at least, in the way I see fasting working for me. Reason being that at the end of each day of fasting, there is a very large amount of food being consumed, and I mean a lot. Fasting is about calorie restriction for sustained amount of time - modern Ramadan (based on the experience I had in Saudi, which is a very conservative country) is not really about restricting calories, but just shifting the time of the day in which A LOT of calories are ingested.

Egyptian here, can confirm this unfortunately. Most here just go all-in when they break their fast. In fact, I would say that they ingest more calories in Ramadan than in regular days. I advise all I know to eat with moderation, but few listen :(

Personally, when I started to eat moderately when fasting, I started to feel much better. Previously, I would be very tired when breaking the fast... I would be so full that I wouldn't be able to do anything except lie down.

I think that the current trends are due to people nowadays seeing it like a mega celebration, and they see that eating a lot and feeling tired after is just a sign of that celebration. Ramadan is more than just fasting, but I am going off-topic.

By the way, there's a sunnah in Islam to fast Monday's and Thursday's. Some here may find it beneficial.

Depending on your intent fasting can be for a lot of things.

The health benefits of fasting aren’t about total calorie restriction, but ARE about shifting when you eat to allow your body to kick over into the fasted state for a period of time to get the benefits of that.

I practice a 24 hour fast once a week, for spiritual and health benefits, not to lose weight, and enjoy a very full dinner after the 24 hour fast.

Ramadan looks very much to me to be about fasting, at least spiritually.

I've heard the same, although it was only with one person I know. I was talking to my friend about Ramadan and how I thought it was a really healthy behavior. She laughed and told me that a lot of people eat garbage (her word, not mine - a lot of fatty and fried foods) and she had to take the initiative to eat healthier stuff during Ramadan.

Still, it definitely gives you the opportunity to reset every year.

In France, from where I stand (I don't have close muslim friends), they also have large meals during the night.

I don't know if that was always the case in history of this religion, maybe in the past the night meal was simply a shared meal with the group, of normal size.

It seems that in your case and mine, we're seeing something that has more to do with symbolism and morals (no gluttony, more thoughtful days, sharing, empathy).

I used to live there too. In the 90s. I doubt total calorie consumption drops during ramadan. Rather, meals just happen at different times.

Ctrl-f also returns no results for Lent. I haven't tried for other religious fasting or abstinent holidays but I'm sure there would be 0 to few mentions. HN skews strongly towards certain industries and demographics so it's a bad sample of "the western world" and it seems that most people posting here would simply lump Ramadan under "religious practices" of which there are several mentions. Most religions include both feasting and fasting practices so I wouldn't single out any single one as more healthy or hurtful for the world.

I agree with the basic premise that religious fasting is an often overlooked but beneficial practice in the modern era.

@zhynn, Buddhists monks eat one meal a day throughout their lives. Even lay Buddhists who maintain 8 precepts do not eat after noon throughout their lives. As a practicing Buddhist I eat during a 4-5 hour window everyday of the year. Why make a big deal about one religion?

Is this true in practice, for most practitioners? It's sometimes hard to tell how ideals match up to reality when it comes to this stuff, for those without first-hand experience. For my part I've read a fair amount about Buddhism but the real-life experience of a lay practitioner or monk remains obscure to me.

In reading about Christian monastics I've found that their fasting practices are, and were even in the middle ages, much less dramatic than they seem at first glance, except in relatively rare cases. For one thing, many fasts aren't so much "don't eat" but "eat somewhat less, but still quite a bit", and there are tons of feast days to counter-balance that. And even those rules are thrown out for older monks and any who are ill, of course. You look at their calendar and think "damn, that's a lot of fasting!" but then you read accounts by actual monks and more detailed sets of rules and find they did very little actual no-eating fasting, in the typical case, and many "fast days" still involve a lot of eating.

In my own Sangha (community) of lay people, we have several who observe the 8 daily precepts. Every retreat I have gone to, I have never seen monks eat more than one meal a day.

> Is this true in practice, for most practitioners?

I think it would be more common to find a lay practitioner adhering to the first five precepts.


But they eat each day in Ramadan (at certain times), don't they? How is it even "fasting" and why should it be mentioned?

There are different kinds of fasting. They don't eat from sun rise until sunset during Ramadan. I'd qualify that as fasting.

Eating once a day or in a limited time period is called "intermittent fasting".

those who "fast" also eats right? like other living being?

Yes. Like the GP mentioned, fasting is a ritualistic practiced in many cultures.

In India, for example, there are fasting days in a month and many have certain days of the week even where they fast.

Great point.

while on fasts, you get an energy level and mental clarity that has to be felt to be believed. everyone should try it at least once.

I have fasted 100 lbs away over the last 2 years. I adhere to an 18/6 time delay eating schedule but have done 2-3 day fasts with 1 refeed meal for a month at a time. I've also done countless 5-7 day fasts. I've gone as long as 12 days with nothing but water. There were many months where I could count the number of times I ate on one hand. My last go was every other day with just one meal on my eating days. I did that this year for all of January to the end of March and would never recommend alternate day fasting to anyone. You will mess your self and your metabolism up. You will lose a lot of muscle. Alternate day fasting should be avoided.

Never over two years did I feel any of the mental clarity or more energy you speak of. I follow guys like Cole (snake diet) and even he speaks of the feeling of dying and lying in bed shivering on a 5-7 day.

Are you sure about the metal clarity and energy levels, because I and the folks I know who fast don't seem to have those affects.

> I've gone as long as 12 days with nothing but water.

This is dangerous and please don't encourage others to do only water fast. Pure water fast is dangerous beyond 4 days or so.

You need to supplement minerals while on per-longed fast. Salt, magnesium and potassium are vital to regulatory processes in your body.

When your body uses up all reserves it will not be able to sustain those processes. It is serious business so please read up on the subject while trying anything longer than 3 days.

> feeling of dying and lying in bed shivering on a 5-7 day.

This is body telling you something is wrong, ignoring is outright stupid. Like ignoring that you are bleeding.

> I have fasted 100 lbs away Congratulations

I remember reading about someone who fasted for an entire year. Of course he was morbidly obese when he started, he took supplements, and he was under strict medical supervision for the duration of the fast. (Sorry, don't remember the source.)


"Starting in June 1965, Scottish man Angus Barbieri (1939 – 7 September 1990) fasted for 382 days. He lived on tea, coffee, soda water and vitamins, living at home in Tayport, Scotland, and frequently visiting Maryfield Hospital for medical evaluation. He lost 276 pounds (125 kg) and set a record for the length of a fast."


I’ve yet to find a form of potassium that doesn’t upset my stomach when fasting. I’ve tried nu-salt, potassium citrate, and cream of tarter so far.

I’m about to give up on total fasts and have bone broth a few times a day for the minerals.

potassium iodide might work for you.

Thanks. I’ll try it out.

Interesting. Any studies that validate the first point? I recall research talking about how there’s little muscle wastage until day 21 in normal healthy adults.

Keen to know if we have learned more in this space

The figure I have seen is that muscle wasting drops to less than 0.2 kg per day once the body fully enter ketosis. Obviously, anyone considering a fast longer than a few days should do so under the supervision of a doctor who can monitor electrolyte levels etc. They can also check for the rare enzyme defect called Medium-chain acyl-CoA dehydrogenase deficiency, those with it are unable to fast safely.

Isn't 0.2 kg per day is a huge amount of muscle?? Thats half a pound a day!

I know this is true just anecdotally. I'm totally ripped after a 7 day fast with none of my muscle wasting away, just the fat.

for salt look up topics around:


Magnesium and potasium main but not only function is to regulate heart beat. Lack of them might lead to arrhythmia and other complications.

Not sure about muscle loss.

I agree, a 12 day fast is dangerous and unnecessary. I was experimenting and would never do it again. Anything longer than a 3 day fast (72 hours) is not necessary.

I didn't say that exactly.

If you supplement minerals and listen to you body response, then you can fast as long as you have fat stores in your body.

Its only dangerous if you don't know what you are doing or ignoring signals from your body. Lightheadedness is common thing people report or /r/fasting/ and almost always they don't take salt while fasting.

But I am not an expert, it feels like I have done more reading about fasting then actual fasting. So don't take advice from strangers (especially /r/fasting or worse dryfasting nutcases).

We need different words, really. You're describing a starvation or calorie reduction fast. More common, and what I practice, is more like a time-shift fast. For example, I exercise in the morning before eating breakfast. This is a fasted state. It trains your body to use fat as fuel. The eventual result of doing this is greater stability in your mood & mind. Your body doesn't crave carbs so much anymore, and you feel good whether or not you've eaten recently.

Your brain runs on carbs. The easiest source of carbs is carb rich food. This is why hangry people seem to want nothing but cookies & candy IMO. But your body can only hold a limited amount of free carbs at any time. Meanwhile, your liver can convert fat to carbs to feed your brain, and your body can hold a virtually unlimited amount of fat. This pathway is more difficult, so you have to train your body to use it.

So I don't think it makes you smarter or more energetic. But it does make you more stable & help avoid the crash.

Not OP, but I agree with you that we need different words. Because what OP is doing is not starvation (till their body is actually wasting away). Having done a few 3 days fasts myself, I can attest to feeling a euphoric energy around day 2 where I felt lighter, and sharper. I have been told it isn't universal, but from the content I have been consuming it has something to do with brain switching to consuming ketones.

Which actually brings me to another point; the brain does not run exclusively on carbs (glucose) - it absolutely has the ability to (and does) functions well on ketones. This is why ketogenic diets can work for many people.

But yes, there's lots of bio-chemical mechanisms that get kicked off when you're fasting for an extended period, so it could be something else that's unique to the people who experience the euphoria.

I am not sure if you've come across this concept, but "Metabolic Flexibility" seems to be trying to explain some of the "after burner" affects of switching around my dieting habits. Where I am no longer exercising strict caloric restrictions, or fasting on a regimen, but I am still observing some of the benefits of when I switched over. (Less bloating, more energetic even after a large meal, less voracious appetite on normal days).

Not eating for few days - is not (yet) starvation, its not 'body wasting away'.

Its a state where your body and mind need to be the sharpest in order to catch food. Or else due to lack of fuel you will enter actual starvation (no fat reserves).

When you have reduced calories intake ~~500kcal a day you are signaling to your body that you can find/catch food but there is not a lot of it. Your metabolism will slow down in order to adjust to reduce calories. You loose muscle mass much faster than when not eating at all.

I have done multiple >3 days fasts and I havent experienced this sharpness feeling though. It seems some people do and some don't.

Also worth mentioning keto is natural diet of Eskimo people, they survived generations eating seal's meat and fat. So keto is not some crazy nutjob diet invention of 21st cent.

My understanding (and experience) is that this clarity is usually just about the lack of all the crap that normally makes you feel awful. Things like sugar, dairy, and processed grains plus preprocessed foods. I've always found that after 10 days, you start to feel amazing and do so for around two weeks more before your body starts to adjust.

The mental clarity comes from adrenaline. When you fast your body slowly uses up its glycogen store and releases adrenaline to compensate. Presumably it does so in order to keep you active / motivated enough to go look for food to refill your glycogen stores. It is this adrenaline that gives you the mental clarity and causes you to have trouble sleeping when on a fast: fasting is essentially natural adderall.

On top of this, once you use up all your glycogen, your body enters a period of autophagy which causes disfunctioning cells and protein fragments to become broken down and reused. This causes your body to function more efficiently, including your brain.

That's true but it's also true that neurogenesis will start at some point during a fast. For me, it's around day 3 or 4. It's an evolutionary mechanism to form new connections in the brain to help find food/survive.

When I fasted I remember the feeling of energy kicking in around day 2-3. I had moments of supreme clarity but also moments of fuzziness. The energy boost was real though. I continued to exercise quite heavily so didn't't see any muscle loss. I'm quite a big guy so there were a lot of fat reserves to melt—my skin became very greasy as if I'd eaten a very fat-heavy meal, I could even taste the oil in my mouth.

I wonder if, if you are not a big eater, then the difference might be less than if you tended to be full of food, digesting away all day and night. Similarly, if there's not a lot of fat on you maybe, rather than burning fat with an energy boost, you end up burning muscle and feel tired?

I’ve never done the long term fasts, but my anecdotal experience also confirms this - I definitely have significantly less mental clarity on any type of fast I’ve done, to the point where it definitely affects my productivity even by end of day 1.

Myself as well. You just hit low blood sugar. Technically not fasting, but I have an appetite so weak I can skip meals easily and will do so if I don’t pay attention. Eventually I just feel very lethargic and enter what I can only conceive of as “starvation” or “energy conservation” mode. It’s not pleasant. I also have trouble with muscular mass being the first thing to go.

I'm pretty much that way, too.

I think I also just become more irritable if it's been too long since the last time I ate. It definitely doesn't seem to improve mental acuity for me, and any kind of physical activity is just going to feel worse. I've never tried any kind of a formal fast, though, so I don't know if there's something to planned schedules that makes it different.

I can kind of see how I might, under some circumstances, enter some kind of a state of quicker thinking after fasting, but I think it would be something similar to sleep deprivation, where you get perhaps a bit "hyper". That's not really a state I necessarily strive for either.

I've also never been overweight, and have always had more trouble gaining weight than getting rid of it. I wonder if that has something to do with it. I suppose the metabolism might be different if you've got some fat stores vs. if you're rather low-fat.

I can understand how fasting could e.g. have differential effects on cancer cells and thus be useful in specific circumstances. I also understand that people have rather different reactions, so I don't doubt that some people achieve some kind of a state that feels good or useful by fasting. But I don't really understand the hype, or calling it a panacea.

I start to get this clarity and energy around the 24 hour mark. It is unmistakable.

Each time I hit that point I get the clarity and energy, and remember that it happens each time. Pretty interesting. So much energy I can't sleep and end up eating when I can't sleep which breaks the fast.

I am only 5kgs over weight at this point if that is relevant for anyone.

Many, many people who follow fasting/ketogenic diets report heightened energy and focus, myself included. This usually comes after the carb/keto flu phase once adjusted to the low carb intake and after the body has gone fully into ketosis. You have to be careful to get enough salt while fasting or eating very low-carb, though, as your body can struggle to hold on to water without those carbs you're used to eating. Consuming too little salt can definitely contribute to feeling sluggish.

You don't follow Cole if you don't know the difference between the effects of dry fasting and wet fasting after 5-7 days. If you do know that, you are purposely making a misleading statement to support your argument.

Same here - I've been eating only one meal a day mon-fri for literally years. I also do 2-3 day fasts here and there, my longest was five days. No changes in mental clarity and energy.

I have been on a 18/6 and 20/4 fasting protocol for 3 months now - few up and downs but mostly sticking to it. The obvious results are weight loss (not so much, I'm within my BMI targets). I can confirm that my mental sharpness has improved but it's not the same every day.

Most days I feel amazing, some other days I feel quite tired and I experience some mental fog. I still haven't found the reason for such an oscillation.

I suspect it has to do with what I eat during the eating window (for instance, more sugarish food, more carbs, etc). I think I should record what I eat and compare it with the overall well-being to get to some conclusions.

I noticed that in the winter, eating mostly fruits would cause a “crash” about ~30mins-1h after my fruity meal (but dang I had a lot of energy during that time). When I ate potatoes, spaghetti, I would have a longer span of energy.

I did a 3 day fast to see what it was all about. The energy levels were not there. I would get tired after a short brisk walk. Physically I was weaker but still had burst strength just no endurance or cardio.

Mentally however I found myself unable to have too many variables in my head and my mind was not more able to focus on something but less distracted with extraneous thoughts. I could if I wanted to shut off the chatter in my brain and meditation became very easy.

It is definitely a different mode for me and I do appreciate it but I'm told that many people in my family have ADD and that I might actually be showing symptoms that would go away when in ketosis.

I don't think that a sudden 3 days fast will bring any immediate benefits (perhaps some weight loss), on the contrary. I see fasting more as a long term, life choice. I do feel more energetic and sharp during fasting.

I recently did a full check-up (I'm 48) and all my blood/urine values were spot on - before starting my fasting protocol some values mostly related to arteriosclerosis were slightly over the recommended values. Obviously, this doesn't say much or it's far from being a scientific proof: it's just an observation. There are good chances that for a lot of people fasting would just not help and make life misearable.

Definitely. I started deopping breakfast. At first it was hell. But you get used to it. Noe I’m down to one meal a day. It’s very convenient, and my energy levels aren’t affected by food intake.

I found my first fast to not be representative of later fasts. You get more accustomed to not eating after you repeat the practice. You become conscious of how often you wander into the kitchen and stick your nose in the refrigerator and the pantry. A cold glass of water becomes a delightful snack.

You might try reducing your fasts to just 24 or 36 hours on weekends.

Currently, I do intermittent fasting where I don't eat before noon or after 6pm, 7 days a week. It helps me to manage my weight, I feel consistently energetic (I work out most days, cardio and weights), my mind feels as clear as ever, and I have no trouble following the practice as a lifestyle.

I'd say that I don't feel quite that clarity of thought when meditating after fasting for 30 hours or so. But it strikes the right balance of achieving some benefits of fasting without feeling like a huge chore that I have to overcome.

I had a period a few years back where I did fasts up to 3 days quite frequently.. Once I got used to it they felt pretty good. But, the point I wanted to add is that they would have been very difficult for me if I wasn't also doing a pretty strict low-carb ketosis diet. Without the hunger control of keto and having my body acclimated to using stored fat as a primary energy source, fasts have been untenable.

Did you supplement with any vitamins or electrolytes? I've done a few 100hr fasts and definitely experienced a decrease in physical energy, but my mental clarity was always improved. I have ADD and use a mix of intermittent fasting and alternate-day fasting as one form of my treatment.

Did you try it more than just for that three days (as in, try multiple fasts over time), and or try other variations of it (eg 16/8 intermittent fasting) to see if one of those might suit you better?

I hear people say this a lot, but I've done plenty of fasting and rarely experienced this, and when I did, it was very mild. I don't know if I'm significantly outside the norm. The noticeable difference is that I feel pretty low energy after about ~24 hours of fasting.

Henry Cavill talked about the extreme dehydration he experiences prior to filming a shirtless scene, to make sure there is no water retention, and how he could 'smell water' from across the room.

It makes sense biologically you would get some heightened awareness mixed with periods of extreme lethargy as your body tried to preserve itself.

Do you have any recommend resources around fasting? or a preferred routine?

I'm very interested in reading more.

The resource I've heard recommended most often is "The Complete Guide to Fasting: Heal Your Body Through Intermittent, Alternate-Day, and Extended Fasting" by Fung and Moore. I just checked-out a copy from my library and will be reading it soon.

I have no idea what a library is but i found this on Amazon for 9 British Roubles.

I felt something a bit similar, that I assume is your brain abandoning the desire for stimulus from food, leading you to go deep into whatever else to feel something. Very nice trick indeed.

i like to persuade people by having them imagine an isolated tiger who hasn't eaten anything in a week. by force of nature their sense of smell, hearing, etc. must all be heightened so as to ensure their survival.

But that's because they are incredibly hungry and food focused, at that point they don't care about taking part in other activities and just want food. That tiger would definitely not be the sort I'd care to be around.

understandably! it will no longer be thinking: human animal, could be dangerous..

but a tiger has evolved to be an apex predator, and not much else.

our predatory speciality is more about leverage than brute force, or scavenging rather than hunting. so i think the logic still applies that cognition can be improved in a way that is beneficial to modern humans. resourcefulness implying that resources are found / conjured when they appeared to be lacking?

How does a fasting mimicking diet (FMD, like the one described in the article) work? I had a skim and didn’t see a detailed explanation. What’s your experience like?

The FMD in the article was approximately 200 calories per day for 3 days, using a standardized set of allowed items (broths, etc.)

This was done in preparation for each chemo treatment.

How long do you need to fast for benefits? Is water the only supplement allowed? Curious

I have a book called Fasting and Eating for Health by Joel Fuhrman MD (ISBN 0-312-18719-X). In it, he recommends fasting for between 10 - 15 days around once every 10 years.

I have actually completed a 10 day water only fast a few months ago (good use of lockdown), it takes my body around 4 to 5 days to switch completely to ketosis, then to the end of the fast I was burning through 1 pound/~0.5 kg of fat per day. You can watch it happen every morning when you weigh yourself.

0.5kg of fat contain 4500 calories, how did you burn 4500 calories per day?

woow, other comment recommending fifteen day fast is a) dangerous and b) doesn't answer your question??

i fast twice per week for ~30 hours and drink copious amounts of tea and coffee. but intermittent fasting also works, the really important information is that ketosis can begin after as little as 12 hours, so basically fast for a minimum 14 hours if you want any effect at all, and everything after that is bonus. no extras in your coffees btw, though a splash of milk / coconut oil in your breakfast coffee is acceptable :)

Where is the evidence that a 15 day fast is dangerous?

i think it would be premature to assume that it had universality in the same way as something like intermittent fasting.

the possibly dangerous part is recommending that particular part of the book in response to a query asking for how long one needs to fast to feel the effects.

I should dig what people were saying about fasting in the previous eras. Of course it's well known how integrated with religion it was but it was never mentioned as a physiological lever.. more like an emotional/moral act.

Also it would be weird to see people in those days, allegedly not having access to the cornucopia of yummy food we have in 2020, going into fasting. Maybe more diseases on average made them realize that the less fed survived better ?

Works for other things too like plants. A bit of stress ends up making them more resilient. Depriving them a bit of water and Sun can make for a stronger plant.

Of course there are limits but when done right you end up with a plant that on average is stronger.

And yet, most of what you said is bullshit that's not evidence based.

"Autophagy", that famous process which supposedly happens during fasting, that miraculously regenerates us, actually happens during caloric restriction, and it's actually a daily process that happens during the night, in everyone, while glycogen stores get naturally depleted.

And we have no evidence that increased autophagy levels are beneficial, quite the contrary, we have some evidence that, right after fasting, the immune system is suppressed. The bigger the caloric restriction, the larger effect on refeeding. An effect very relevant for malnourished populations that suddenly get access to food.

This is basically modern quackery, medical technobabble lacking any evidence other than obscure studies done on mice.

What "healers" and witches used to do, but taken to the next level.

And unfortunately it is also a recipe for serious eating disorders. Hello anorexia.

"bullshit", "quackery", ""healers" and witches"

Is all that really necessary?

When it comes to human health, the unknowns are legion. Medical science is in its infancy, but too many act as though it's a mature discipline built upon rock-solid theories with few problems.

20 years ago, I noticed that my mental fog cleared up and I felt healthier when I ate very low carb, I looked to pioneers like Atkins and others who predicted my results much better than those pushing the "food pyramid". Those pioneers were called "quacks". I was told over and over by supposed experts: "Calories in equals calories out.", "A calorie is just a calorie.", "You're going to ruin your kidneys on a high protein, high fat diet.", and on and on.

The problem isn't science. Science is the best method we have to discover the nature reality. The problem is with science used as a religion or political weapon without humility or appreciation of its flaws and limitations.

The food pyramid was never backed by any high quality evidence. It was primarily pushed by various agriculture lobbies.

Calories in calories out is 100% valid for weight loss. The problem is that people interpret it to somehow be a claim on overall health when it is just a statement on weight gain and loss, which while can be beneficial to health, isn't everything.

A calorie is just a calorie, so much as color is color. Its a single property of food that can be compared. If you want to lose weight that is the property you primarily need to look at. If you care about overall health then obviously there is a lot more to it than just calories. People somehow interpreted a calorie is just a calorie as a claim that all food is the same when its just saying that from a weight loss perspective, the energy component from any food source is the same -- there are no further claims about nutrition content.

"The food pyramid was never backed by any high quality evidence"

And yet medical organizations backed government efforts to force it upon our society.

"Calories in calories out is 100% valid for weight loss" "A calorie is just a calorie, so much as color is color."

Yeah, and you can tell an obese person to cut off their legs to lose weight. Sure, you'll be factually accurate, but are you honestly talking about weight loss?

"If you care about overall health then obviously there is a lot more to it than just calories."

Is weight loss without health considerations really the subject you think people discuss when they talk about weight loss? Nobody talking about actual dieting and weight loss is talking about thermodynamics. We're talking about the complex interactions between food, exercise, mental health, and our individual bodies in order to reliably lose weight and be healthier.

Actually there are well documented cases where not all calories are good and the same high sugar diet leads to more diabetes.

> "Autophagy", that famous process which supposedly happens during fasting, that miraculously regenerates us, actually happens during caloric restriction, and it's actually a daily process that happens during the night, in everyone, while glycogen stores get naturally depleted.

Last I looked into it, we didn't really know the autophagy timeline in humans, because we can't really measure it. Of course there's a natural fasting window that every human adheres to while they sleep, but with food available at all times, three meals a day plus snacks, that window may be far smaller than what the body is evolutionarily adapted to. What if autophagy doesn't kick in properly until 10, 12 or 14 hours?

Fasting isn't about starving yourself, or being malnourished. When you do eat, you should be getting plenty of calories, and eating well, not garbage.

Skipping a few days of food while being overweight (the vast majority of people in the west) won't do any of what you listed though. You're probably confusing "starving" and "fasting".

Fasting != malnourishment tho.

Anecdotally, I've been doing 16/8, 20/4 intermittent fasting and a couple of 24-48h fasts over the past 10 years and have not yet developed anorexia.

I've been doing 16/8 for the past year+ and I've barely lost any weight (BMI of 25.5ish but I'm muscular). I've always been quite comfortable going without food for 16 hours, so I'm never even hungry.

Someone recently posted a link on HN to a book by an Herbert Shelton MD that you might find interesting:


Cancer needs sugar. One of the primary ways they detect cancer is via a PET-CT with a radioactive glucose tracer. It lights up where glucose uptake is the highest. This article talks about starving cells going into defensive repair mode, but also about how energy-hungry cancer cells are.

I had cancer (lymphoma) and did three years of chemo (mostly maintenance/preventative, as it was wiped out in the first couple months). I actually gained an enormous amount of weight, because the steroids I was on (and all the weed I smoked) made me ravenously hungry. If I end up in that situation again, I'm going to make a concerted effort to dramatically reduce my calorie intake, and in particularly carbs, because I've read a lot about the potential benefits of starving the cancer out.

A young biology researcher pitched in to explain the warburg factor in tumors, he made a long paragraph explaining the oh so twisted metabolysm of cancerous cells. The amount of counter intuitive disruptions that mechanically benefited the tumoral tissue was .. almost impressive.

Could you give examples?

I forgot but let me try:

- cancerous cells often break the mitochondria forcing cell into a secondary respiration mode

- they also trigger vascular growth but chaotically

- since the cell is in this alternative respiration, they don't need normal arteries to get energy so the chaotic arterial network they grow is not a problem

- IIRC this network also impedes chemotoxins to reach the cell as fast as normal cells

- if you starve your body from sugar, you'll hurt the normal cells (which are in full respiration mode) while the cancerous will keep their metabolysm

It was a bunch of things like this but when you take distance, you have a dysfunctional cell that somehow is setup to construct a near perfect bed of survival in his own destructive processes.. it's almost smart.

Good stuff.

Also of note is tumor heterogenity. Not only are cancers different between cell origin and across different patients, cancer is not one uniform genetic entity even inside a single person.

Why? The cancer's ability to repair DNA mutations is crap, so different chunks of tumor can rapidly evolve different mutations.

You might be able to drug one portion of the tumor based on a fancy receptor/biomarker, but that tumor chunk will get outcompeted by a different cancer blob that doesn't express that.

Yes, and this was ignored for quite a while at least at the mainstream level.

I've read not too long ago that a tumor is actually mostly an outer layer of active cells, the inner is made up of dead tumors probably serving as nutrient (<= very blurry on this). yet another part of that strange anti-life living form named cancer.

Oh Steroids and weed now that is some serious munchies - I used to joke the prednisolone (a common steroid) was the Homer Simson drug.


Almost no one reads these papers when stuff like this gets posted on HN.

And there is shameful statistical fuckery afoot in this paper. People are only repeating the hype statistics at the top of the paper.

Their "pathological response" rates touted at the top of paper only come from the 1/3 of women able to actually carry out the diet. This is the "per-protocol" language in the abstract. An honest evaluation here would be "intention to treat" and analyze chemo responses in every assigned to each arm.

And they do that evaulation, but bury it later in their paper. Turns out when you account for the 2/3 of women who can't do that fasting, there's NO DIFFERENCE in response rate:

   "The overall pCR rate was 11.7% and did not differ between the two groups (10.8% in FMD group versus 12.7% in control group; OR 0.830, 95% CI 0.282–2.442, P = 0.735."

A lot of people might think "Ah, well, fasting is clearly effective for the 1/3 that are able to carry it out, just gotta make sure you have the willpower to be the 1/3."

But hold on. Slow down. There's a good chance the "women who fasted had better chemo responses" story completely REVERSES cause and effect. Here's how:

    WOMEN 1 - Has indolent biology, slower growing tumor than your average breast cancer at this stage.
 - Symptoms: Less pain, neuropathy, less swelling, tumors not affecting distant organs as much

    WOMEN 2 - Has aggressive biology, faster growing tumor than your average breast cancer at this stage.
 - Symptoms: More pain, neuropathy, more swelling, tumors begin to affect distant organs
So ask yourself: Which women is more likely to be able to follow a strictly regimented diet?

Clearly WOMEN 1.

This is like making people with cancer do an Ironman triathalon.

People about to enter hospice and pass on in a few weeks are gonna be way less able to complete it than someone who has months left to live.

But all you've done is stratify your patients.

The triathalon doesn't make anyone live longer.

That's absolutely right and it's a major problem of this study. There is one caveat though, in the most common ER+ breast cancer, radiological response is more predictive of survival than pCR. And in this study, they do observe a better radiological response in the fasting group, even when looking at ITT (though just barely significant).

Looks like this study was initiated/sponsored by this company, specifically testing the effectiveness on what they call Fasting Mimicking Diet.


If I understand correctly this is a low-calorie diet, which is easier to follow than a strict water-only diet, but they claim it is equally effective. They recommend it also for healthy individuals, 5 days a month. Does anyone have experience with it?

Just from personal experience, I've found that fasting is actually easier that something like a fast-mimicking diet. Maybe there's something physiological going on, or maybe it's just psychological, but I find it much harder to eat a little bit than to just not eat. Then when I do get to eat, I can eat enough to feel satisfied.

drinking light vegetable broth?

I do actually, did it twice this year one week in January and then again during lockdown during the last week of March I think. I heard about it from the guy who came up with it, he wrote a book about the merits of a Mediterranean plant-based diet (with the occasional fish, but no meat) that resonated quite well with me, since it's easy to implement and also really delicious - I mean there isn't really all that much that go wrong with eating vegetables, some bread and pasta, nuts, olive oil, and fish (also had the welcome side-effect to reduce my meat-consumption to pretty much zero now)

Anyway, so after I switched my diet I decided to give his FMD a go and was pleasantly surprised - it's pretty tough, the second and third day were the worst for me, I was just incredibly hungry (and honestly speaking I did'n really achieve any mental clarity during those days), just went on a ton of walks. But I felt I gained a lot of mental strength following that experience, it was easier for me change eating or drinking habits simply because this exercise of control over your most basic need really provides you with a boost of confidence.

You obviously also lose a lot of weight (around 4kg per week) and I've lost even more since then, maybe 20kg since the beginning of the year (though that's a combination of sport, this pescatarian Mediterranean diet, but probably also those 2 fasting sessions). I plan on doing it again, though I want to try out 'real' water fasting next time. I think this is a great starting-point into fasting, though.

Thanks for sharing!

My little advice would be to pick a right season of the year(if you live in 4 seasons). If you start fasting, from day 2-3 you would feel cold. And if outside is around 0 C and you have to walk somewhere, wind blows, it's not nice. Even sitting in regular office feels colder then.

Correct me if I'm missing something, but this isn't the type of fasting most people in the thread are talking about.

In the study they say "FMD" or "Fasting mimicking diet", in particular, Xentigen (ProLon?), which is sold by L-Nutra. These are "healthy plant-based meals". [0]

[0] https://l-nutra.com/pages/prolon-nutritional-information

At approximately 200 calories per day for 3 days.

If this turns out to be true, then the practice through the centuries, of a "Religious Pilgrimage" might be effective too. Walking all day, with little food, would put someone in a calorie deficit, combined the stress of extraneous exercise might trigger cell death in cancer cells.

Perhaps, completely changing one's environment. Example going from a city to live in a forrest, might also trigger different genetic pathways, and awaken the immune system.

Many narrative stories have this pattern of someone getting sick and retreating, going into nature, in pursuit of fresh air or sunshine.

Since this is likely to attract a lot of fasting practicioners to the comments I want to ask - I've occasionally tried out fasting or severe calorie restriction in the past but I always seem to get dizzy, weak and shaky in the first 24 hours and have to give up. This seems like a normal physiological response to be honest, how are people either avoiding or coping with this?

Crawl > walk > run

Try eating breakfast at 10 am instead of 8(let’s say) for a couple of weeks.

Then see if you can hold off until noon without going to bed later.

If you can eat between the window of noon and 8PM you’re effectively on a 16/8 diet.

After you’re comfortable, try eating no later than 6PM, then try 4PM. Before you know it you’re on a 20/4 schedule.

I've been doing some variant of intermittent fasting for about 8 years now. Of course, I'm not always consistent. There have been days, weeks or even months when I'm not disciplined.

At least in my experience, the sense of hunger is extremely tuned to one's internal clock. The body seems to absolutely know at what time of day it expects to eat. If I go a long time and never eat before 6 PM, I won't feel even a tinge of hunger until the evening. If I go on vacation, and eat lunch for a week, then the next day I'm ravenous by 12 PM.

The hardest thing about fasting is the transition. Once you've got a pattern, your body seems to pretty much just adjust and it becomes just as normal and effortless as eating breakfast, lunch and dinner. I say that because a lot of people try out fasting for a few days, suffer enormously and decide that the juice isn't worth the squeeze. Whereas I think if you get over the transition hump, most will find it's not nearly as bad as it seems to be when you first start out.

One technique that I think makes for a smooth transition is a modified version of partial fasting. To start, instead of completely abstaining during the fast window, restrict yourself to vegetables and berries. Don't touch the higher caloric density foods like meats, dairy, and starches inside the fast window. Truth be told, this probably isn't that bad a diet just to stay on forever, because it ups vegetable consumption so much. But if your goal is full fasting, it's a good way to make a full transition. Your body's internal clock starts getting used to much lower calories consumption in the fast window, but you don't have to feel like you're starving.

I’m by no means an expert, but I think there’s some amount of adaptation that occurs. I feel like I had to “train” my body to fast. I had a similar problem and it was really unpleasant the first time I tried a fast, but recently did a three day fast with no discomfort right until the end. The end was weird because I told myself I was going to break my fast, and my stomach kicked into action too early, making me sick. Like I went from very little hunger to RAVENOUS. Had to break my fast at a drive through (best chalupa I’ve ever tasted!)

For me at least I go into fasting by first skipping breakfast for a few days, then skipping breakfast and lunch. Skipping dinner is mostly a mental hurdle because there’s so much psychological signaling that you should eat at dinner time and don’t really know what else to do with yourself. Going to bed without eating in a day feels weird at first.

I also make sure to get lots of electrolytes during all of this, magnesium glycinate and lite salt seem to do the trick. Otherwise I start to get shaky and have bad headaches.

I had a similar experience with my first extended fast. I was just going to do three days, but I felt really good and not at all hungry at that point, so I extended it a day. But when went to break the fast, as soon as I started eating the light salad and broth I had made, I became instantly ravenous and no longer had any self control. So what started as a light salad ended with mozzarella sticks and a whole pack of Oreos. I no longer keep junk food in the house if I'm doing a fast.

The salt and other electrolytes is crucial as you mentioned. If you don't supplement you'll actually get some pretty intense cravings. It was the first time I understood why deer love salt licks. I would have licked on one of those like it was a tootsie pop.

huh, I guess this is why I love pickles and kimchi when I'm cutting calories

I think it's pretty normal. I don't know for sure, but it's possible that it's more or less the same effect as keto-flu.

Make sure that you get plenty of water and electrolytes.

Also, if 24 hours is too much, you can try intermittent fasting, and do 16 to 20 hour fasts.

+1 on starting out with 16 hour fasts.

It also seems that some people can't tolerate fasting for whatever reason, so GP might just not be cut out for it.

It's tricky, make sure you drink enough water, but not too much (too much water washes out too much salt from your body, dropping your blood pressure too low). A backup plan if this doesn't work is bone broth soup. It's not a lot of calories so keeps you in the fasting state and can pick you up pretty nicely. Salt the soup but not too much. The key seems to be to keep your electrolyte levels in the Goldilocks-zone.

Everyone has a differing body chemistry. I can only speak for myself. I do have some mild symptoms when starting a fast, but they go away quite quickly. It could be related to the fact that I'm not usually hungry in the mornings (excluding having done heavy exercise) and can quite easily go most the day without eating and from there it is not much of a stretch to go another day and another...

Not recommended but I just kind of white knuckled it through the experience and it settled down pretty quickly after that. In subsequent fasts you have the visceral memory of it getting better and those negative experiences aren’t amplified by the doubt of the whole process.

There's something called snake juice, which is just a mixture of water and salts. Apparently this helps balance electrolytes which solves the problems you're experiencing.

Water with a little bit of salt solved this for me. But I am not a doctor so I don't know how good or bad it is.

I'm not doubting the results (yet), but I just can't understand how is this possible. Chemotherapy basically damages host cells, with a lot of collateral damage. It already can cause all sorts of digestive tract problems and weight loss among other things. And now they propose to cut energy intake even more. How is this beneficial I can't understand.

Chemotherapy is tuned to kill cells that divide. Cancer cells happen to divide a lot, but sometimes normal healthy cells do too. (Not all of them.) Thus they become collateral damage along the cancerous ones. Hence nausea and other unpleasant effects.

If you can persuade the normal healthy cells to hunker down and stop dividing for a while, the killing effect of the drugs will concentrate on the cancerous cells alone. This is what fasting is expected to achieve. It is not alone in this regard, anything that inhibits mTOR (e.g. rapamycin) should in theory have similar effect.

Got it, thanks for explanation

The idea, as far as I understand it, is that fasting makes cells more quiescent and less likely to undergo mitosis. But cancer cells cannot respond the same way and continue dividing, causing more specific uptake of chemo drugs that damage cells during mitosis. Fewer bystanders get damaged.

Interesting. Though cancers that force you to fast, like stomach or esophageal cancer don't have great 5 year survival rates.

That's what I keep thinking. One wrinkle here is that the calorie restricted days are those leading up to chemo, which were the only days my dad (who had esophageal cancer) could eat very much.

How could we know if this was survivorship bias? What if the folks who can best comply with the calorie restrictions are those who are already in a good state?

Their "better response rate" touted at the top ignores the 2/3 of women who couldn't carry out the assigned FMD.

When you fold back in those 2/3 of people on that arm, the response rate is the same:

   "The overall pCR rate was 11.7% and did not differ between the two groups (10.8% in FMD group versus 12.7% in control group; OR 0.830, 95% CI 0.282–2.442, P = 0.735)."

What are the recommended ways to fast? I did intermittent fasting for about 5 months to shed 25lbs. It likely contributed, but I was also laser focused on dropping.

I've been doing intermittent fasting for 5 weeks as of today and in that time have lost 22 pounds. I have more energy and have noticed a generally heightened sense of well-being (though perhaps as a result of the weight loss and improved appearance).

I am doing 18:6, so I generally eat from 12pm to 6pm. During that time I typically eat two meals, and one or two small snacks. I try to eat pretty healthy, but there have been plenty of times in the past 5 weeks when I've just pigged out at Waffle House. I still have lost significant weight.

I have two major recommendations: first, drink tons of water. I try to drink about 16oz of water every hour. Besides hydration, it helps a lot with hunger. You will get hungry at times. For me it isn't every day - some days it's easy to stay on track. Others, it's tough. When you're feeling hungry, chug water. It really helps. (tip: try sparkling water to change things up if you get sick of regular flat water).

Second, I recommend using an app to track your fasting. Mine was free and tracks your start and end times for fasting and tells you how long until your fasting period is over. It also lets you track your weight, and even water drinking progress if you want.

Last thing - the hardest day of fasting, by far, is the very first day. After that, it will get easier.

ETA another tip: If you're doing it for weight loss, don't weigh yourself every day. Your weight will fluctuate a pound or two from one day to the next, and even throughout the day. It can be demoralizing to fast for a day and then the scales tell you that you're up a pound. Instead, weigh yourself maybe twice a week, and always near the end of your fasting period.

I've found 20:4 successful only as a means of preventing me from eating too much; prior to IF I'd habitually graze throughout the day. It's basically a diet where you don't have to think that much about what you eat (you should a bit, still, obviously).

If you aggressively fast on chemo you must must must take vitamins. Have seen personally what can happen when one does this without supplementing and have a result of low levels of thiamine which is lethal and has life long effects when it isn't.

I wonder how much the effect is slowing metabolism relative to cancer cells.

Fasting has been practiced for millennia, but only recently studies have shed light on its role in adaptive cellular responses that reduce oxidative damage and inflammation, optimize energy metabolism and bolster cellular protection. In lower eukaryotes, chronic fasting extends longevity in part by reprogramming metabolic and stress resistance pathways. In rodents intermittent or periodic fasting protects against diabetes, cancers, heart disease and neurodegeneration, while in humans it helps reduce obesity, hypertension, asthma and rheumatoid arthritis. Thus, fasting has the potential to delay aging and help prevent and treat diseases while minimizing the side effects caused by chronic dietary interventions.

-- Longo and Mattson


I haven't read the article yet but I just want to point out something that may be fairly important to understand here: chemotherapy drugs target cellular division. This means that if fasting slows down cellular division in normal cells but not cancer cells, it could make the chemotherapy drugs able to target the cancer cells more selectively than normal. However, this would not necessarily translate into anything relating to situations in which chemotherapy drugs are not being taken.

> Essentially, fasting causes a switch in healthy cells from a proliferative state towards a maintenance and repair state.

Is this autophagy?

In this interview with Dr. Eileen White, Chief Scientific Officer at the Rutgers Cancer Institute, she mentions that certain types of cancer cells can actually use the effects of autophagy to survive.


If you read “Tripping over the Truth: The Metabolic Theory of Cancer”[0], the fundamentals of this are discussed quite extensively. Highly recommended for anyone interested in both fasting and cancer.

[0] https://www.goodreads.com/book/show/23496164

Fasting also has excellent results for treating many illnesses including mental ones. There is a documentary that covers two clinics that offer fasting as a treatment and scientific research in this area.


In case anyone else, like me, saw "pCR" and didn't know what it meant, I believe that it means "pathologic complete response". Not "polymerase chain reaction" which is all you get by googling.

It's really unfortunate people use overloaded acronyms like this without a definition.

Wish fasting was a part of our culture more regularly.

With almost half of America now obese, we are seeing the downside of ignoring good diet as COVID devastates those suffering from obesity and diabetes.

Reproducibility crisis.

EDIT: I had a misled belief. Here's a better source: https://www.cancer.org/treatment/treatments-and-side-effects...

Ignore below...

Wasn't the whole impetus for getting "medicinal" marijuana for the snacking? Seems like someone is talking out both sides of their mouth.

Nonetheless glad to see additional evidence for fasting's multiple benefits.

The use of marijuana for chemo patients is to manage the extreme nausea that accompanies the treatment. It's not about the munchies per se.

Noted, thank you

I wonder if a regular keto diet would work. In the study they use the term "fasting mimicking diet".

Did not expect this.

> Fasting improves chemotherapy results

Does it mean more deaths or less?

In mice.

Have you clicked on the link? It's a result from an RCT in women with locally advanced breast cancer.

In his defence the abstract starts by talking about mice, which is a bit confusing. Sure they talk about patients as well but it's not immediately clear that mice can't be considered patients. If you read on it becomes clear though!

The title saying it's a multi-centre phase 2 trial makes it extremely clear. You don't do those in animals.

On the contrary. It worked in mice, so they tried it on humans; turns out it works in humans too.

The first sentence was misleading to me as well (it does refer to mice, but only as a "was also effective on mice" sense), but the study was done on humans.

Or perhaps, fasting is the cure, and can even undo the harm from chemo!

If I'm reading this correctly, the "harm from chemo" to the person was about the same, but the "harm from chemo" to the cancer was much more significant in the fasting group.

Yes. But there are alternative healing ideas that fasting and juicing in themselves can cure cancer.

Extraordinary claims require extraordinary evidence.

Please provide your extraordinary evidence. Ideally in the form of multiple strong, well-vetted and well respected studies in peer-reviewed journals. Otherwise I'll presume you're full of it.

Absolutely. Let's look at the claims.

What is the first claim though? Is it that extraordinary evidence needs to be provided for the claim that a poison (chemotherapy) is a cure for cancer?

You will likely say that there is evidence in "multiple strong, well-vetted and well respected studies in peer-reviewed journals".

But then I would question the authority of peer-reviewed journals. Do know about replication crisis?

https://www.bbc.com/news/science-environment-39054778 : "According to a survey published in the journal Nature last summer, more than 70% of researchers have tried and failed to reproduce another scientist's experiments."

https://en.wikipedia.org/wiki/Replication_crisis : "a number of efforts have been made to re-investigate classic results, to determine both the reliability of the results and, if found to be unreliable, the reasons for the failure of replication."

Another reason I dismiss most scientific authority is on account of funding. If funding is controlled by government, the military and private corporations (as it is), then this triad can cooperate to fund or de-fund whatever studies they like.

To see what I mean about funding, we can look at my imagined idea that 'you want to prove the health benefit of cold potatoes'. First you can fund 10 studies. Let's say 2 support the thesis, 2 refute it and 6 are inconclusive. You can then further fund the 2 that support it. And rinse and repeat. Pretty soon you could have enough studies to create a whole new field exclaiming the wonder of cold potatoes.

Unfortunately, this really is how science works. Science is a money making operation, and is politicised. A common sense idea like fasting for cancer, or not eating carbohydrates to get rid of diabetes, has no economic benefit. Scientists themselves can work within the system with good intentions, but can be more or less unaware of the machinations and agendas at play.

If you want to talk about solutions, you would take a totally different tack. At present we have a sickness not a wellness industry. Companies get money from you when you are sick. The more sick you are, the better it is for their monetary return. The ideal patient is someone who will be ill for a long time, which is a perverse incentive. Really, you want a wellness industry, where if you are well, those ensuring your health get paid. As they are incentivised to keep you well, you should expect good advice - their financial well-being depends on it.

> Is it that extraordinary evidence needs to be provided for the claim that a poison (chemotherapy) is a cure for cancer?

Let's start by not conflating all kinds of cancer and all kinds of chemotherapy, because it's not a single disease, and the outcomes vary greatly.

But, for instance, survival rates for testicular cancer have risen significantly (or even dramatically) since the invention and introduction of the chemotherapy treatment that is being used for it today. If detection isn't overly delayed, the cure rate in the developed world today is around 95 to 100 percent.

So let's please, please, please, not go for cheap "chemotherapy = poison" rhetoric. I have first-hand experience with the adverse effects, but you can't dismiss a nearly 100% cure rate.


Regarding what you more generally wrote, it's true that financial interests affect and direct the pharma industry. There are several adverse effects from that, such as research not being directed at areas with potential health benefits but low profitability, and also over-marketing (and thus possibly over-prescription) in other areas. It would also be great if medical research were less tightly bound to funding from the industry and rather got its funding from public sources instead. (That wouldn't make it non-politicized, but direct financial interests might not be as significantly involved.)

But it would be rather misguided to think that there aren't actual working treatments coming out of the industry and research as well. Sometimes those treatments are the difference between life and death. Let's not discount that.


The significantly improved survival rates for TC are pretty well-known, but a couple of sources:




edit: line breaks between URLs

Thanks for your thoughtful reply.

I don't say that there are no good things coming out of the medical industry. Sometimes there are good things, and when it comes to bodily trauma, I think the medical profession is excellent at stitching people back together again.

But I'm especially interested in wellness and optimal living. I genuinely don't feel the industry has anything to offer on that front. Food is probably the most important 'treatment' we can do, but the industry is pretty silent on this.

My anecdotal experience, is with a relative who was diagnosed with diabetes. It was never explained to them that if they don't eat carbs they won't have the disease - cutting out bread, rice, etc was too 'out there'. The advice was about how to manage the process, cut back a little on the bread, inject insulin etc - the relative ended up on a high level of medication. I think all that could have been avoided by eating appropriately for the disease, advice which that person has taken (a bit) with a corresponding drop in symptoms + medication. To my mind, it is not so radical to cut those foods out of the diet completely if they are harmful!

Its not that doctors intend to be mean or harmful, but they are taught in such a narrow way with medication at the heart of what they do. If they advise 'off menu' they stand to lose their license. The medical industry is in fact captured and beholden to big pharma.

Did you even know that there are alternative theories of disease? Namely - the terrain theory (Beauchamp). That what you eat and how you live is the main cause of disease. That disease (of all sorts) is a natural bodily process, as your body tries to heal - including cancer. Eg, at a lower level, when you have a cold, this is your body clearing your system. There is mucus and a fever. The worst thing to do is to take medication to suppress this process - but that is the first thing most of us will do.

Anyway, for that and other reasons, I find the terrain theory makes a lot of sense, and it is something that does not require an intermediary to tell you what you need to do (eg a doctor, testing, etc). If you get it right you enjoy optimal health. That is the position that I'm arguing from - that food and proper management of what and how we eat (inc breaks such as fasting) is probably the best healer. If I were ever seriously ill, my first course of action would be as per my initial comment - a prolonged juice fast.


I don't know that particular theory, but I don't think it would really make sense to try and have a unified theory of disease, alternative or otherwise. (I don't think medical science really even tries to have one.)

Various diseases have such different causes that we cannot really expect to proscribe a common theory to them. The symptoms of cold are mostly caused by the immune reaction (and medical doctors also acknowledge that). Sometimes you may need to curb that immune reaction e.g. with antipyretic medication because the reaction could be disproportionately strong and be dangerous in and of itself; sometimes it may be best to just let it be. Sometimes it doesn't really matter one way or the other, and you could either take symptom-relieving medication to ease how you feel or elect not to.

(FWIW, I generally prefer not to take medication for a cold, partially because it doesn't help the healing -- in the case of cold, only time does -- and partially because artificially improving the symptoms might make you feel better than you actually are and thus make you believe you can already do more when you should still rest. So I kind of agree with you that people may take medication too lightly in some cases, but I certainly wouldn't treat all disease the same, because different disease are very different in many regards.)

In cancer, your own cells have begun to divide and grow uncontrollably. Normally cells have various kinds of built-in controls for growth and longevity; in cancer those controls have failed, and not just one of them but a number of them at once. Since there's always a nonzero probability of a mutation causing one of those mechanisms to fail, there's always a smaller but still nonzero probability of enough of them failing that the result is going to be a malignant tumor.

I fail to see why we should consider a tumorous growth as a reaction of the body trying to heal itself from something else. First of all, from what; and secondly, how would that even begin to accomplish the goal? On the other hand, the generally accepted understanding that it's just cells where enough things have wrong that they have gone into uncontrolled division and growth makes perfect sense.

Again, your immune system is going to (or at least should) react to that, but that's not what causes the disease, or perhaps not even most of the symptoms. (I lack the understanding to comment on how much of the immediate symptoms of cancer are caused by immune reaction, not to mention that cancer is again not a single consistent disease, but in any case, let's not pretend that cells that are nonfunctional and uncontrollably taking over space from your healthy tissue isn't going to be a disaster in most cases regardless of that.)

Also, many factors influence the risk of cancer, including nutrition. That's also undoubtedly true of many other diseases, and medical science agrees on that. (Different studies might come up with different results on what exactly those factors might be, but that's largely due to the complexity of the topic.) In some disease (e.g. cardiovascular) it might even be the most significant one.


It's true that medicine traditionally focuses on treating disease, not on what generates wellness beyond that. I agree that there's a lot that can be achieved outside of medicine that can be beneficial for wellness (and even health).

It's also true that big pharma probably has an effect on doctors and their education. However, I don't think that makes medicine generally suspect. Rather, the truth is more nuanced and in between. Doctors, especially at major hospitals, have significant clinical experience in their fields, and that's not immediately affected by pharmacological research. Also, not all medical (or even all pharmacological) research is funded by the industry. Criticism of big pharma or even medical research is not without merit, but I think the impression I get from your comments is too cynical of the field.

While wellness is something where it's often best to listen to yourself, I would urge anyone with serious illness to seek medical treatment. That's certainly so at least in case of disease such as cancer which have well-established and evidence-based treatments.

Thanks again for your thoughtful reply.

The terrain model is well worth looking into. It works of the principle that the body has all the abilities it needs to manage itself, but that issues arise when we overload it. So if we eat bad food, too many toxins, etc our system cannot cope and force a response. Initially that would be something like a cold. But when things are more serious, it progress and tries to isolate toxicity, hence cancer. Did you know that cancer does not survive in an alcaline environment? But that sugar, coffee, carbs, etc are acid forming?

I think your instinct is right about allowing a cold to proceed naturally. Medical intervention is not necessary. What you really want is dark mucus to be released - you are really clearing out your system at the point.

You are right to say that I am very cynical about big pharma. I am. There is simply no incentive for them to heal you, and every incentive for them to support you in a protracted disease. Their profits are best when they are managing you all the way down.

Unfortunately, if you are working on a very long term plan, and have huge resources, it isn't as complex as you think to create a situation where the medical establishment works in service of big pharma. You would need to capture the governance steering apparatus only - ie that bit that gets to say what is a valid treatment or not. And then you wait for that to feed through the system. I think that the US medical system has been run that way since 1940's.

So... you have nothing? That is what I figured.

I'm saying neither of us has anything.

But that you are making a mistake in thinking you do have something.

I asked for evidence. Rather than providing any you went on a diatribe about science. Until you can provide any reasonable evidence of your claim, you are nothing but a crank.

Yes - it was a diatribe about science but I thought there was a reason for it.

You assume that poisoning people to kill the cancer is a sensible treatment. There is supportive evidence for that, but I'm saying the evidence should not be accepted. The 'evidence' is actually PR for big pharma, not the unbiased evidence you think it is.

So, from my point of view, we both have no evidence.

But I am saying you are mislead when you think you have evidence.

Wouldn't that be relatively easy to find evidence for? We could look at the change in cancer of Muslim communities during Ramadan?

Well, there are lots of types of fasting. Juice or water or nothing. Skipping a meal, or not eating solid foods for 3 months. IMO not eating during the day but then eating a lot at night might not be the best type of fast.

But even so, it would be interesting to see numbers anyway.

Ramadan is not really fasting these days. Most people do feasts every day (or something close to every day) on Ramadan when the sun goes down.

Tell that to Steve Jobs...

What, you're telling me someone tried an alternative healing, and died! That's a scandal.... lock them up!

Obviously, I'm joking.

But did you know that iatrogenic deaths - deaths caused by doctors - are the 3rd largest cause of death in the US?

And when you see the numbers, bear in mind that these are only the official reported numbers! I can only imagine how many other deaths must be caused by doctors but get explained as natural deaths.

PS in case anyone stumbles on this and wants to look deeper, I just recollected one of the pioneers of this sort of treatment: The Gerson Institute - https://gerson.org/

If you have to provide a simple (ELI5, if you mention one scientific word their eyes rollup into their skull etc..) way to view how fasting 'controls' the cancerous growth in the body... sadhguru makes an easily digestible concept of 'crime' in the body [1]. [1] https://www.youtube.com/watch?v=JWnyTJ96upw

ELI5 means break down the science into simple concepts that a 5 year old could understand.

Not here is some Deepak Chopra figure to explain it to you in voodoo

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