THE KETO DIET

The ketogenic diet has made huge waves in the world of weight loss. People have gone from morbid obesity to a healthy weight range and given all credit to this low carb diet. BUT… the million-dollar question is, is this a viable option for athletes who want to improve their body composition? 

Athletes thrive off of healthy, complex carbohydrates. They fuel hours of intense training. So… how could it be healthy for athletes to cut out this entire food group? Do athletes NEED carbs to train hard? Will a keto diet completely wipe all energy? Let’s find out from the experts. 

Our first study looks at 21 strength trained women who were randomly assigned to either a ketogenic diet or a non-ketogenic diet. The study looked at body composition and strength levels. Findings indicate that a keto diet may help to decrease fat mass and maintain fat-free mass after eight 8 weeks in trained-women, but is suboptimal for increasing fat-free mass. 

The next study looks at the effect of a four-week ketogenic diet on exercise metabolism in male and female CrossFit-trained athletes. The study found that ketogenic diets in males led to an increase in fat utilization, but not in females. The conclusion is that Male CrossFit-trained athletes seem to be more prone to shifts in macronutrient utilization (in favor of fat utilization) during submaximal intensity exercise under a ketogenic diet than are female athletes.

The third study will look at the effects of a ketogenic diet for endurance athletes. This study looks at 4 female and 1 male endurance athletes who underwent a 10-week ketogenic dietary intervention. All athletes increased their ability to utilize fat as a fuel source, including at higher exercise intensities. Athletes reported experiencing reduced energy levels initially, followed by a return of high levels thereafter, especially during exercise, but an inability to easily undertake high intense bouts. Also, each athlete reported experiencing enhanced well-being, included improved recovery, improvements in skin conditions and reduced inflammation. Overall, there were performance decrements and negative experiences, but athletes were interested in continuing the low carb, high fat eating style due to the unexpected health benefits. 

In the final study we will look at the ketogenic diet in context of exercise performance. It has been concluded that ketogenic diets may impair exercise performance at higher intensities. For athletes concerned with anaerobic power and strength, short-term consumption of low carb/ketogenic diets does not negatively affect these performance parameters but may lead to unwelcomed decreases in lean body mass or blunted skeletal muscle hypertrophy. Therefore, the literature does not support the use of ketogenic diets as an effective dietary strategy to increase athletic performance.

The common denominator of these studies is that a ketogenic diet is not conducive to building lean mass. As an elite athlete, building muscle is essential for everything that we do. It reduces chance of injury, it makes us more explosive, powerful, resilient… 

It is also known that the benefits of a ketogenic diet are not confirmed long term. Proving that this diet may be helpful to kick start fat loss in obese/overweight people, but possibly have less significant effects after 6 months. As an athlete, it is safe bet to stay away from an extremely low carb diet unless it is recommended by a doctor. If you would like to decrease your body fat percentage, there are more beneficial ways to go about it. 

CITATIONS: 

Vargas-Molina, S., Petro, J.L., Romance, R. et al. Effects of a ketogenic diet on body composition and strength in trained women. J Int Soc Sports Nutr 17, 19 (2020). 

Durkalec-Michalski, K., Nowaczyk, P.M. & Siedzik, K. Effect of a four-week ketogenic diet on exercise metabolism in CrossFit-trained athletes. J Int Soc Sports Nutr 16, 16 (2019). 

Zinn, C., Wood, M., Williden, M. et al. Ketogenic diet benefits body composition and well-being but not performance in a pilot case study of New Zealand endurance athletes. J Int Soc Sports Nutr 14, 22 (2017).

Harvey, Kristin L et al. “Ketogenic Diets and Exercise Performance.” Nutrientsvol. 11,10 2296. 26 Sep. 2019, doi:10.3390/nu11102296