Protein is a crucial macronutrient for exercise and performance because it provides a foundation for increases in size, strength, speed, and hypertrophy (1). However, protein requirements for a carbohydrate adapted athlete and a ketogenic adapted athlete may be slightly different due to the stricter macronutrient guidelines of ketogenic diet and protein sparing capacity of being in a state of ketosis. Furthermore, protein requirements vary based on sport, training, periodization cycle, and the individual goals; therefore, it is likely that there will be a large variability in protein intake from individual to individual.
Current recommendations for protein requirements for the average individual are 0.8g per kilogram of bodyweight. For a 200-pound male, this is approximately 73g of protein per day (2). As activity increases, protein requirements also increase due to the need for additional substrate to repair tissue, increase protein turnover and maintain positive protein balance, as well as promote recovery (3).
For the recreational athlete, recommendations for protein intake range from 0.8g per kilogram of bodyweight to 1.2g per kilogram of body weight, for the strength and power athlete this number is increased to 1.5-2.2g per kilogram of body weight, and for the endurance type athlete 1.2-1.5g per kilogram of body weight (4). It has been speculated that protein intake over 2.2g per kilogram of body weight has no benefits on hypertrophy and will ultimately result in fat gain (3). However, recent research out of Dr. Jose Antonio’s lab (5) demonstrated that protein intake at 3.4g per kilogram of body weight lead to greater decreases in fat mass and body fat percentage compared to a normal protein group (2.3g/kg) during a six-week resistance training program. What is even more interesting is that the high protein group consumed more total calories than the normal protein group, but improvements in body composition were favored towards the high protein group. Although this data does not link directly to performance, but rather body composition, it is great information to have if reduced body fat and increased lean muscle mass are needed for optimal performance.
In regards to ketogenic dieting, performance, and protein intake, the same general rules apply. However, if you recall the proper ketogenic macronutrient distribution is 75-80% fats, ~5% carbohydrates, and 15-25% protein. For most individuals, 20-25% protein is around 1.5-1.8g per kilogram of body weight. The reason protein cannot exceed this amount is because of a process called gluconeogenesis. Protein may be converted to glucose in the liver via gluconeogenesis. Despite this limitation to protein, there is much debate behind gluconeogenesis and ketogenic dieting. With this in mind, we suggest starting in the 15-25% range and titrating up as you see fit for your desired goals, activities.
When it comes to sources of protein, whole foods are likely the best option for a ketogenic adapted athlete. This is because of the theory that concentrated sources of amino acids have the potential to initiate an insulin response (6). Therefore, using traditional supplements such as whey protein isolate, whey protein concentrate, casein protein, egg white protein, and branched chain amino acid supplements (BCAA’s) may not be advantageous for an athlete following a ketogenic diet while trying to maintain stable blood glucose levels; however, much more research is needed in this area. When trying to keto-adapt, the goal is to keep insulin low. Insulin is secreted by the pancreas in the presence of carbohydrates and possibly concentrated sources of amino acids. For example, glutamine has been shown to be glucogenic, which means that when carbohydrates are needed glutamine can be converted to glucose. Furthermore, branched chain amino acids, specifically leucine, is a ketogenic amino acid and could actually increase acetoacetate levels. Therefore, straight protein shakes or concentrated amounts of protein are not recommended. However, if you create a “fat shake” as a morning meal or meal replacement, this can serve as a good method for incorporating both healthy fats and protein in order to achieve a strong satiating effect.