HomeAnswersIs keto good for endurance athletes?

Is keto good for endurance athletes?

This question is about Nutrition, Running and Cycling
Sarah Achleithner
No, at this time, limited research shows no clear performance benefits to athletes following a ketogenic diet — endurance or otherwise [1,2]. 
The keto diet is a high fat, very low carb diet, where carbohydrate intake is typically limited to 30-50g per day. The keto diet has two big downsides for athletes: limited glucose availability and increased oxygen demands. Although fat burning increases following a keto diet, endurance capacity in keto-adapted athletes still appears to be limited by glucose availability [2]. A keto-adapted athlete will simply have less glucose available to fuel a long ride than a carbohydrate-fed competitor, and research to date suggests that this impairs performance, even if carbohydrate is temporarily restored pre-ride [2,3].
Another reason why keto is inferior to higher carbohydrate diets for endurance performance is that ATP (energy) production from fatty acids requires more oxygen than ATP production from glucose [2, 3]. Higher oxygen demands during exercise equate to lower efficiency, thus limiting the potential performance benefits for athletes following a strict ketogenic diet.
Keto spelled out in food on a brown background
[1] Kerksick, C. M., Wilborn, C. D., Roberts, M. D., Smith-Ryan, A., Kleiner, S. M., Jäger, R., Collins, R., Cooke, M., Davis, J. N., Galvan, E., Greenwood, M., Lowery, L. M., Wildman, R., Antonio, J., & Kreider, R. B. (2018). ISSN exercise & sports nutrition review update: research & recommendations. Journal of the International Society of Sports Nutrition, 15(1). https://doi.org/10.1186/s12970-018-0242-y
[2] McSwiney, F. T., Doyle, L., Plews, D. J., & Zinn, C. (2019). Impact Of Ketogenic Diet On Athletes: Current Insights. Open access journal of sports medicine, 10, 171–183. https://doi.org/10.2147/OAJSM.S180409
[3] Burke, L. M., Sharma, A. P., Heikura, I. A., Forbes, S. F., Holloway, M., McKay, A., Bone, J. L., Leckey, J. J., Welvaert, M., & Ross, M. L. (2020). Crisis of confidence averted: Impairment of exercise economy and performance in elite race walkers by ketogenic low carbohydrate, high fat (LCHF) diet is reproducible. PloS one, 15(6), e0234027. https://doi.org/10.1371/journal.pone.0234027