[com2kid]

There is plenty of work showing that physical endurance increases after extended periods on keto. Athletes have carefully tracked their performance numbers day by day and demonstrated real changes.

And as someone who participates in activities that require large amounts of endurance, I know on keto my ability to perform for extended periods of time is higher. These aren't "I think" numbers, they are "polar heart rate monitor strapped to my chest" numbers.

The very nature of keto leads to improved endurance, fat is a much more plentiful energy source than glucose, it may be less efficient (lifting heavy on keto is a well known problem), but it /never/ runs out. If someone is doing an activity that doesn't cause excessive lactic acid build up or complete muscle fatigue, then a keto will give an endurance advantage.

[bad_user]

> There is plenty of work showing that physical endurance increases after extended periods on keto

Not really.

Yes, athletes do suffer an adaptation, but it's basically about returning to near baseline levels (i.e. from sucking badly to sucking less). And as a matter of fact, the peak performance never recovers to full capacity ;-)

Here's a list of studies on this subject — all of them showing a dicrease in performance:

- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2279002/

- https://www.ncbi.nlm.nih.gov/pubmed/14967870

- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4113752/

There's also this one that shows no difference in endurance performance at low/moderate intensity, a far cry from your claim:

https://www.ncbi.nlm.nih.gov/pubmed/6865776

And endurance exercise could see a benefit in some circumstances, although this is highly debatable, however also in athletes a keto diet can lead to lean mass being lost:

https://commons.lib.jmu.edu/master201019/109/

[throwaway_tech]

>Yes, athletes do suffer an adaptation

You admit and acknowledge an "adaptation" in this comment, but in another reply to me where I talk out the keto adaptation, you replied:

>everything you're saying is a complete myth. Define what it means for the cells to adapt for "running on ketones". There's no such thing.

As previously provided:

A ketogenic diet (KD) involves using fat, a high-density substrate, as the main source in daily calorie intake while restricting carbohydrate intake [21,22]. In this way, the liver is forced to produce and release ketone bodies into the circulation [23,24,25,26]. This phenomenon is called nutritional ketosis [27,28,29]. Over time, the body will acclimate to using ketone bodies as a primary fuel, which is called keto-adaptation, an element of fat-adaptation [30,31,32]. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6410243/

>Several days of dietary carbohydrate restriction to levels < 40–50 g/day, with moderate protein, results in increased circulating beta-hydroxybutyrate (BOHB) by an order of magnitude. When maintained for several consecutive weeks, the metabolic state of ‘nutritional ketosis’ awakens a dormant set of genes and metabolic programs that counteract insulin resistance and manifest in several positive health outcomes. This process, referred to as ‘keto-adaptation’, is characterized by accelerated rates of whole body fatty acid oxidation, while glycolysis, insulin concentrations, insulin receptor activation and signaling, constitutive inflammation and oxidative stress are all decreased. https://www.sciencedirect.com/science/article/abs/pii/S24682....

>Here's a list of studies on this subject — all of them showing a dicrease in performance:

I think most agree for high level athletes in anaerobic sports ketosis isn't going to be the best diet for athletic performance, but these studies don't really support what you claim

- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2279002/

>In conclusion, in this study we have demonstrated that VLDL-TG made a significant contribution to fuel utilization during exercise after adaptation to a fat-rich diet. The increased total fat oxidation observed after fat diet adaptation originated from both a higher plasma FA oxidation and utilization of VLDL-TG, and thus circulating VLDL-TG should be included among the lipid fuels that may be utilized during exercise.

- https://www.ncbi.nlm.nih.gov/pubmed/14967870

>Adaptation to a 6-week HFMP diet in non-highly trained men resulted in increased fat oxidation during exercise and small decrements in peak power output and endurance performance.

- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4113752/

This is the most supportive of your position, but it still acknowledges the benefits of ketosis

>It can be concluded that long-term, high fat diets may be favorable for aerobic endurance athletes, during the preparatory season, when a high volume and low to moderate intensity of training loads predominate in the training process. High volume training on a ketogenic diet increases fat metabolism during exercise, reduces body mass and fat content and decreases post exercise muscle damage.

[mountain_peak]

Not claiming that the science is settled, but I when I entered keto over 10 years ago (TL:DR daily 10K+ 'performance' runner, neuropathy from glucose intolerance - genetic, avoid all drugs), I wanted to be sure that I could run without ingesting carbs (since everyone said you couldn't).

Read "The Art and Science of Low Carbohydrate Performance" and can absolutely say that after an initial horrible period that lasted for months, I was eventually able to run further and just as fast as I used to when I was carbo-loading. I can honestly say that running is more difficult now - my legs are generally sore and I don't feel like I'm 'flying along', but I've always tracked my times with Garmin, then Apple, and the stats belie how I feel.

From the book: "[Keto-adaptation] allows even a very lean (10% body fat) athlete access to more than 40,000 kcal from body fat, rather than starting a prolonged event depending primarily on ~2000 kcal of glycogen."

I think the studies you quoted would back-up the authors, but I also wanted to lend my long-term personal experience. I can't recall where I read it, but thought adaption also occurred in leg muscles where they found a massive increase in the number of mitochondria for athletes on keto.

I tested myself daily for years until I found a combination of diet and exercise that worked. My body definitely adapted and became much more efficient at burning fat - there's no performance 'wall' anymore, but I think the experience is different for everyone.