Does keto affect performance?

This question is about Nutrition and RunningCycling
Sarah Achleithner
Yes, following a keto diet can reduce exercise performance in events requiring maximum or near-maximum effort [1]. However, the keto diet appears to be less detrimental for low and moderate-intensity exercise after the adaptation period. 
The keto diet is a high fat, very low carb eating approach, where carbohydrate intake is restricted to less than 50g/day. Studies have found that those on a keto diet performed 4-15% lower than those eating a high carbohydrate diet [1]. In addition, athletes on a keto diet experience early onset fatigue during short-duration activities [2]. 
While keto may be less detrimental for submaximal exercise, athletes may fall short on nutrients such as fiber, calcium, magnesium, selenium, vitamin C and B-vitamins which can potentially impact performance. For more information on the ketogenic diet for athletic performance check out this article.
Ketogenic foods including bacon, greens, cheese and avocado, on a white plate on a white background
[1] Wroble, K. A., Trott, M. N., Schweitzer, G. G., Rahman, R. S., Kelly, P. V., & Weiss, E. P. (2019). Low-carbohydrate, ketogenic diet impairs anaerobic exercise performance in exercise-trained women and men: a randomized-sequence crossover trial. The Journal of sports medicine and physical fitness, 59(4), 600–607.
[2] Chang, C. K., Borer, K., & Lin, P. J. (2017). Low-Carbohydrate-High-Fat Diet: Can it Help Exercise Performance?. Journal of human kinetics, 56, 81–92.