The lowest quintile in this study were consuming 46,4% of kcal from carbs (that's about 230 gram of carbs for a 2000 kcal total intake). Not even close to low carb by today's standard in the health blogosphere.
The authors make this explicit in the discussion section:
>>> However, the absence of association between low carbohydrate intake (eg, <50% of energy) and health outcomes does not provide support for very low carbohydrate diets. Importantly, a certain amount of carbohydrate is necessary to meet short-term energy demands during physical activity and so moderate intakes (eg, 50–55% of energy) are likely to be more appropriate than either very high or very low carbohydrate intakes.
The missing concept (in the brief quote in your comment) might be "fat adaptation", which takes (in my experience) 2-4 weeks (details: http://www.artandscienceoflowcarb.com/the-art-and-science-of... )
One certainly can fuel activity with carbohydrates, but a fat-adapted person should have no trouble with physical activity on a (very) low carbohydrate diet. Interestingly, a fat-adapted athlete can still use carbohydrates for supplemental fuel before, during, or immediately following extreme exertion (no adaptation is required for short-term use of carbohydrates).
It is still unclear, and dubious to claim, that you can operate at 80+ percent VO2 max on hard work outs. Maybe for short workouts or workouts with bursts of activity e.g. basketball.
You can also undo fat adaptation pretty easily. The answer is it depends, but there is little evidence it has any large negative effects. Questions on peak performance vs "feeling fine" will be interesting to see in studies.
The thing is you can use RPE. We basically mean sustained 4/5 effort (rating of perceived on a scale of 1-5). It's a good enough proxy. VO2 max is also tricky because some people have higher or lower VO2 max but go faster or slower. Higher max != Faster times.
I think the sweet spot for very low carb diets is ultra marathon where you keep your HR around 130-140 anyway, wherein you would use fat anyway. Simple fact is you can't max your power output in an aerobic capacity without carbs. This is not disputed. What we want to know is where the cut off point is in terms of percentage of VO2 max.
Edit: just adding, Noakes talks about ultra performance in his book. It covers everything I saw in that book. He dives deep into the body systems and energy production of the body to suss out the science involved.
I actually spent a fair bit of time delivering VO2 max tests to athletes (in a previous life as an exercise physiology lab volunteer).
This comment has me wondering if I still know any active researchers in this area, looking for ideas...
But note that the context of this study is healthspan and mortality, not athletic performance, weight loss, etc.
It was just warning that this study does not warrant that keto diet is good for your health in the long term. The title is a bit misleading.
Why would they make such a claim? Anyone who has done keto and worked out has probably had the experience of doing quite a lot of physical activity while having had no carbohydrate intake at all for half a day before, or more.
Must see if you want to understand/practice keto right:
As far as my research into keto goes eating too much carbs kicks you out of ketosis (duh!) and eating too much protein triggers gluconeogenesis which also kicks you out of ketosis. Which is a shame because I'd be happy to eat fatty steak and fatty pork all the time!
Keto guidelines generally say 30g carbs per day and that's what I'm going to stick to (net carbs; I want to eat avocados!). So typical keto diet should work fine with what you say about carb requirement.
I don't have any particular desire to go all the way to 0 (or some really low number) and if I have some carb budget left I'm happy to get a latte.
Starbucks says grande almond latte has 9g carbs (5g sugars). Perfect to tidy it up to just below 30g/day.
Since I switched to keto I have an amazing mental clarity. Literally from the moment I open my eyes in the morning I feel lucid (before I'd take me maybe 30 min and maybe a coffee to "wake up"). And I feel lucid all the way until I fall asleep (I don't get tired before falling asleep. Just go to bed, sleep). Nice and steady energy throughout the day.
Also, I feel noticeably better overall. My max strength suffered a little bit (keto can take 1-3 months to adjust) but I'm more energetic throughout the day, mind and body.
That is also my knowledge. Therefore, there seems no need for any intake of carbohydrates; So the claim about "needing carbohydrates" is not warranted (about intake, anyway)
At low circulating insulin levels, most cells in your body can efficiently metabolize fatty acids. For the minority of cells that cannot, your liver converts protein into sugar by a process known as gluconeogenesis.
It’s very possible to be a performance athlete and eat very low carb.
In a sessile starvation state glycogen stops being a meaningful energy source after 2 days, with the majority of it depleted in approximately 8-12 hrs (it's non-linear).
Depending on one's baseline physical activity and what they mean by "half a day," sure, glycogen stores can be reasonably depleted.
That said, glucogenic amino acids can replenish glucose stores, which can ultimately become glycogen. Glycogen remains low only in the context of low-carb and low-total calories, so what glycogen is replenished is soon exhausted.
It may be that you disagree, but I get the feeling that you ignored the "doing keto" part of my setup, and instead thought that the person in question was eating cake 12.5 hours before the workout. :)
The depth of color indicates how concentrated ketones are in your urine, which is impacted by (1) the amount of ketones your body is producing, and, very importantly, (2) your hydration level (i.e. how diluted your urine is).
For newbies, if the stick is pink AT ALL, congrats, you're in ketosis. Don't make the depth of color a big goal.
As someone who has been on a low-carb diet for 3 years, on and off, I definitely don't notice any difference in performance, mood or productivity while on a low-carb diet. Too many people (esp. those in a desk job) over estimate their physical activity levels and think they need more carbs.
Sure, if you're an athlete, all this doesn't apply to you. But, for the vast majority (who in the present day) lead highly sedentary lifestyles, it's about time we encourage them to get off carbs as much as possible.
"Gluconeogenesis is extremely expensive" 
Be careful making any changes to your diet based on these "findings". The healthiest populations on the planet eat plenty of carbs, but not refined sugars.
What's really surprising is how many people on here are like, "of course, ketogenic diets!" Where is all the skepticism that is so vividly on display when discussing the latest Google or Facebook product announcement?
I'm sure that encapsulating your carbs in a nice hard-to-unwrap cellulose structure slows the release of this D-glucose stuff and gives your body's control loop more chance to cope. But at this point we're arguing about the details of the causal link.
1. The study "did not analyze which specific source of carbohydrates (e.g., sugar/refined carbs versus whole-grain products) may contribute to the detrimental effects of carbs observed, especially since income and wealth do impact the quality of dietary choices significantly."
This is HUGE. Any study or person that attempts to label an entire macronutrient as "bad" or "evil" is not helping anyone understand the whole picture. The most nutritious foods in the world are carbs. Many of the least nutritious foods are also carbs. Not distinguishing the two gets us nowhere.
2. With this study and most high fat/keto diet studies as well, the timeline is not long enough to tell us about true "lifespan" impact. This one is over 7.4 years. I know it's more difficult to do 10, 20, 30 year studies, but until something can be correlated over those timespans, I would not bet everything on that diet for longevity. There are a handful of generational studies, and almost all have shown that "high carb" or more specifically "plant based" ARE good for longevity. Not saying high fat aren't good for longevity as well, but we have yet to really see examples yet.
3. As many who have tried Keto specifically will tell you (as some have mentioned in the comments), it is very difficult to maintain a ketogenic state. You have to be very disciplined, and this is made harder when you are a social person. This is a big problem when talking about diet and longevity. If it's not fairly easy to maintain, then it's not a feasible diet for longevity where the average person is concerned.
4. As someone else mentioned, the percentage of carbs that the studies participants were eating were not even close to the level required for a Keto Diet
Instead I have taken a simpler approach: I observe the lifestyles of people who are healthy and live a long time. I have observed that eating simply "good, old-fashioned" home cooked food is important. My grandmother lived into her 90s. Ate fat and carbs. Julia Child lived into her 90s. Ate fat and carbs. Edna Lewis lived into her 90s. Ate fat and carbs. I could go on. Just do what they did and you'll have as good a chance as any.
Same for exercise. We already know how to exercise but there are always people who want to make money by repackaging it.
People have survived smoking a cigar a day for decades, but that's a terrible reason to justify the habit, especially when information says otherwise in the other 99% of cases.
Especially, with something related to diet and nutrition, there is an ever evolving need to alter our habits with the way our lifestyles changed. The kind of life your grandmother led is vastly different than the way you do now.
Similarly, carbs were great when as a culture we embraced agriculture, started working the fields and were able to secure food supplies for emergencies and the next generation. Now, farm productivities have shot up, fewer of us are working directly on growing food and there's abundance of food choices all around. We no longer need the easy glucose that we needed earlier. So, it is important that we change our dietary choices if we want to lead healthier lives.
The trouble comes with the way society has been conditioned to have carbs with every meal. Like 90% of the food my peer group eats are surrounded in carbs. Even for a company-wide lunch in the office: the go-to is usually a couple dozen pizzas.
Once you’ve lived low carb for a long time you look at people in line at a coffee house grabbing a bagel and a milkshake and just feel bad for the crash they will have later.
I’m happy to see Keto becoming more and more socially known. Accessiblity around low carb options is getting better and better. My favorite will always be a protein style burger from In-N-Out though.
It doesn't have to be so binary.
Try aiming for a modest level of carbs. I aimed for 40% of calories from carbs, and ended up around 30-35%. That was a significant reduction, but nowhere near what most would consider low carb.
At that level of carbs you can have tacos, and pizza, and those other things. You might have to tweak some of them (add more meat to your pizza, for example) or pair them with other dishes to balance them out, but tweaking is a lot easier than foregoing them.
Are the very low carb diets better? It's unclear but even if they are, a merely OK diet that you can stick to long term is better than a great diet that you cannot stick to.
Will this work for you? Maybe not--one of the most important things researchers are learning is that there is no one size fits all in diet. It worked well for me , and it is pretty easy to try, so why not give it a shot?
I picked 40% as a first goal because it is easy to compute from the nutrition label. Take calories, divide by 10, and change the unit from "calories" to "grams", and that is how many grams of carbs that food can have and still meet the 40% goal.
To see if the whole meal meets the goal, just do the check for each item, and keep track of the total of the differences between cal/10 and g carbs for each item.
For example, suppose you are considered a Wendy's double with cheese, and large fries. The burger is 810 calories, 36g of carbs. 81 > 36, so it easily meets the 40% goal. The fries are 530 calories, 64g of carbs. 53 < 64, so they are over the goal. But how about the meal as a whole? You could add the calories, and add the carbs, and compare, but better is to look at how many carbs you would need to add or remove to each item without changing the calories to make it 40%.
For the burger, you could add 45g of carbs and meet the goal. For the fries, you would have to remove 11g of carbs, or add -11g carbs. 45g + -11g = 34g of carbs. Your proposed meal is OK.
Now suppose that afternoon you have the chance to have a chocolate chip cookie. 200 calories, 30g carbs. It's over 40% (20 < 30) by 10g. But you were ahead 34g after your earlier meal, so you can have the cookie and still be OK for that day. Having the cookie brings you to 24g ahead for the day.
What I did was try to make sure that the first meal of the day had lots of protein and fat, so that I would be ahead by quite a bit. I'd then keep track mentally of how far ahead I was during the day, and would try to avoid letting myself get behind.
In theory there is nothing wrong with letting yourself get behind at breakfast or lunch, and making it up at dinner. In practice, though, that means that if anything happens that disrupts your dinner plans you could end up behind for the day. If you start ahead disruptions are less likely to blow the whole day.
 Result: 140 pounds lost over 18 months, and stable weight since then (six months). (Also a drop in blood sugar, from an A1C of 8.1 on multiple diabetes meds to 4.8 on no meds. I've been under 5 for the last six months, and my doctor removed the diagnoses of diabetes from my chart).
For emergencies, I keep a few shaker bottles in my car with protein power already added. I just add water if we go somewhere with no keto options.
The worst part is not being able to eat/drink at social events, and dehydration.
The best part is never feeling hungry, stable energy levels throughout the day, and not needing to sleep as much.
I also tend to binge a lot when off keto...
Probably on carbohydrates because that is why everyone here is "on and off".
Mainly asking because my diet yesterday was a six pack of Kirin Ichiban beer, a double cheeseburger, and a large P. Terry's chocolate shake, and I felt fine and still had a very productive day. I want to know why I'm able to tolerate stuff like that, and how/if that armor might start falling off as I get older.
One example goes through him talking about the self-experimentation he's done with the diet and the variations of it. From memory, it was pretty informative (albeit general) on the chemistry/biology surrounding it.
I am pretty sure that isn't conditioning. Eating a burger with no chips is just plain wrong, and the same the other way around as well. When I am eating rice and meat together, if I eat just meat, it doesn't taste good. It is so specific, that there is a specific amount of rice that has to go with the meat. Everyone knows this. That can't possibly be conditioning. People complain of "too little rice", "too much meat" etc. No one could have been conditioned so specifically.
This section of the article does not correspond to the title. In fact it seemed all over the place, then goes on to conclude ‘maybe it’s refined sugars.’
I heard this for years and years, but it doesn't pass the sniff test for me.
Go try to eat a stick of butter. Drink some straight cream. Chew on the fat that comes with your beef roast. Sip sausage grease. Drink straight olive oil.
All of these things are hard to do. If I get past two or three hundred calories with any of them, I am workin for it.
I have this drink in the morning, 240 calories of butter and coconut oil in tea, and oh my goodness is that thing substantial. Finishing it is sometimes a bit of work.
But how easy is it to drink 300 calories of sugar and not notice it? Veeeeeeeeeery easy.
I think the idea that what makes food easy to overconsume is volume... I think this idea is so obviously wrong that I wonder if it was ever tested. It certainly doesn't seem subjectively true. Everyone knows rich food is hard to eat!
I haven't tried sausage grease (hard to get the temperature right?), but I have happily done all the others, and the only reason I don't today is because I don't want the calories.
Not everyone is the same.
I hate associational studies like this which don't distinguish between types of carbohydrates (sugar vs starch) or other factors, like whether they were eating whole meals of natural foods or snacking on potato chips 24/7.
But at least they've finally noticed they were completely wrong about saturated fat for 80 years.
Stick to fibrous veggies, beans, nuts, some fruit (berries are best), and you'll be just fine eating carbs.
I'm not contesting the fact that ketogenic diets work for people. But this study is kinda bullshit since it's basically alluding to the worst kind of high GI refined carbs
So does this mean the glucosamine chondroitin pills I take for my joints will help reduce glucose conversion and extend my lifespan?
The summary text says there's causality. A few paragraphs into the study, the text interchangeably uses causality and correlation:
>> found that carbohydrate intake was associated with increased total mortality.
>> By contrast, any type of dietary fat reduced the likelihood of dying.
See my comment: https://news.ycombinator.com/item?id=15465516
Eliminate sugar, increase saturated fat. This study provides little guidance on question “is total keto good or not”.