Rethink Keto: Why Consuming Dairy & Other High-Fat Foods Impedes Performance

Jun 14, 2019

While once only embraced by diet culture, the low-carb craze has begun to infiltrate the nutrient regimens of athletes. Instead of using the most convenient and natural form of energy—carbohydrates—those who follow this diet philosophy predominantly rely on animal-based fat and protein stores to get them through a workout. While some may claim to make gains in the gym, those who take this idea too far can not only hold themselves back in regards to performance, but also wreak long-term havoc on their bodies. An analysis conducted by a diverse group of sports nutrition scientists and researchers (see the full study for the list of authors) addressed the implications of the high-fat, low-carb diet in athletes, concluding that those who wish to excel and maintain overall health should steer clear of this fad.

First, it must be noted that while the authors represent a well-rounded pool of perspectives and specialties, this analysis was sponsored by The Alliance for Potato Research and Education, which could present a conflict of interest. We have questioned studies funded by the dairy industry that are purposefully designed to promote dairy, therefore we have combed through this particular publication to ensure the conclusion is valid and unbiased. The findings below represent information backed by science and research, not special interest dollars.

Our Body Needs Carbs

The authors began by conceding that an athletes’ needs for protein and some fats are actually higher than previously thought. However, there is no denying that carbohydrates are essential for sustained daily athletic performance. Of the three macronutrients, carbohydrates are the most efficiently metabolized (converted into energy) and the only macronutrient that can be readily utilized for energy to supply the fast-twitch muscles used during periods of high-intensity exercise. Athletes who deprive themselves of sufficient carbohydrate intake can suffer during workouts, as they simply refuse their body of the energy it needs to perform this type of energy-guzzling movement.

Carbohydrates (in addition to protein and some fat) are also necessary for a proper and speedy recovery. Athletes must replenish their glycogen stores (the energy stored as glucose) after intense exercise in order to fuel their future workouts. It’s like a long road trip—after you deplete the tank, you have to fill up to continue your journey the next day. Those who cannot rely on adequate glycogen stores can feel fatigued and unable to perform at their optimal best. Researchers cited a study which found carbohydrate-deprived athletes to experience “impaired cognitive performance and mood, perceptions of fatigue, and an inability to focus” (1).

Low-Carb Diets Affect Every Kind of Athlete

Researchers advised against low-carb diets for athletes across the board—from endurance to strength sports. Those who participate in extended physical challenges need to replenish with carbohydrates, as our bodies require more carbohydrates as they become dehydrated. The dairy industry even admits this, as it touts chocolate milk as an optimal recovery beverage due to it carbohydrate content (for more on why chocolate cows’ milk is NOT beneficial, see this article). In regards to strength athletes, those who emphasize protein often consume this macronutrient in place of carbohydrates, leading to an unnecessary surplus of protein and a significant carbohydrate deficiency, ironically leaving them weaker, not stronger.

How does this relate to the Switch4Good mission? Low-carb athletes tend to seek out animal-based sources of fat and protein, relying on foods like milk and whey protein powder for pre- and post-workout meals. Beyond the implications of carbohydrate deficiency as stated above, consuming dairy can severely limit athletic performance by creating excess mucus, contributing to inflammation, and slowing recovery. The authors of this analysis concluded that “whole, natural foods are the best choice for athletes,” specifying that “whole” and “natural” pertain to fruit, vegetable, and grain sources—because there is nothing natural about humans drinking cows’ milk.


  1. Achten J, Halson SL, Moseley L, et al. Higher dietary carbohydrate content during intensified running training results in better maintenance of performance and mood state. J Appl Physiol. 2004;96(4):1331–1340.

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