Performance Drops Along With Weight on Ketogenic Diets Interview with:

Edward "Ted" Weiss, Ph.D. Associate Professor Department of Nutrition and Dietetics Saint Louis University Saint Louis MO 63104

Dr. Weiss

Edward “Ted” Weiss, Ph.D.
Department of Nutrition and Dietetics
Saint Louis University
Saint Louis MO 63104 What is the background for this study? What are the main findings?

Response: Ketogenic diets are popular. They are very low in carbohydrate, with moderate protein and large amounts of fat. They are popular for weight loss but definitive studies of this are lacking.

We tested the effects of a ketogenic diet on high-intensity exercise performance, such as sprinting. The result showed that the ketogenic diet was harmful to performance, reducing performance by 6 – 7% when compared to a high-carbohydrate diet. What should clinicians and patients take away from your report?

Response: Ketogenic diets may unknowingly harm exercise performance for athletes. Non-athletes may also suffer negative effects from ketogenic diets because many tasks, such as climbing stairs, require the same physiologic systems as athletes use for high-intensity exercise.

Therefore, athletes and most people in the general population should follow the broadly accepted guidelines to consume adequate amounts of carbohydrate in their diets, preferably from healthy sources such as fruits, whole grains, and legumes. What recommendations do you have for future research as a result of this study?

Response: Future studies can add to these findings by evaluating longer-term effects of ketogenic diets on exercise performance, and by studying the effects of these diets on other types of exercise performance, such as weight lifting performance. Because ketogenic diets cause the body to become more acidic, they may also have adverse effects on health but more research is needed on this topic.

I have no relevant financial or other conflicts of interest to disclose. Thank you for your contribution to the community.


Wroble KA, Trott MN, Schweitzer GG, Rahman RS, Kelly PV, Weiss EP. Low-carbohydrate, ketogenic diet impairs anaerobic exercise performance in exercise-trained women and men: a randomized-sequence crossover trial. J Sports Med Phys Fitness 2018 Apr 04. DOI: 10.23736/S0022-4707.18.08318-4

Note: Content is Not intended as medical advice. Please consult your health care provider regarding your specific medical condition and questions. 

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