That might be part of the reason the keto diet is thought to be a better fit for endurance athletes. But even for them, evidence is mixed. "The ketogenic diet has been popular with athletes that engage in long endurance events, because it requires them to rely on less frequent carbohydrate feedings to fuel their exercise (think gummies, drinks, and goos) and more on their body fat stores," Brown explains. "This can decrease uncomfortable gastrointestinal symptoms (fewer stops at the porta-potties!), but a keto diet can be as challenging to maintain for an athlete as it is for a layperson."