Keto diets and ketone supplements have gained popularity among endurance runners for their potential to delay fatigue, but new research suggests they do not give athletes an advantage.
A review of keto diet studies published in medical journal Sports Health: A Multidisciplinary Approach did not identify any significant advantages or disadvantages for endurance runners’ aerobic performance from following a ketogenic diet or having ketone supplements.
When taking part in a continuous activity such as running that increases the heart rate, our cells use oxygen to produce energy. As aerobic performance improves, the heart, lungs, and muscles work more efficiently to allow us to keep active for longer without tiring.
The review findings add weight to a warning by the International Society of Sports Nutrition that, for ultra marathon runners, following a ketogenic diet produces a range of negative symptoms. These include fatigue, headaches, poor concentration, lethargy, gastrointestinal discomfort, nausea and weight loss.
“There is no evidence that a keto diet can improve endurance performance, and plenty that it can’t. There is evidence that it is possibly bad for your bones and evidence that increasing carb intake likely improves performance,” says Andy DuBois, head coach at Mile 27 Endurance Coaching, based in Australia, commenting on the review.