To be effective in terms of vitality, ketogenic diets require that you're not in the "gray zone", characterized by a simultaneous insufficient intake of fats and just enough carbohydrates, which hinders ketosis but doesn't provide enough energy in the form of carbohydrates. Conversely, a seasoned athlete on a keto diet could theoretically cyclically have a much more substantial carbohydrate intake (and not just enough! ~ 100gr) after intense training such as bodybuilding to recharge muscle glycogen stores for improved performance, without struggling to return to ketosis several hours or days later. This is a hypothesis, an avenue to be explored, which some ketogenic athletes call metabolic flexibility, i.e. the ability to switch from one fuel to another fairly quickly, a capacity few people can claim.