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throwaway_tech | 6 years ago
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|6 years ago
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.