There is still some conjecture surrounding the maximum amount of protein that can be utilized for muscle-building purposes in a single meal for those who undergo consistent resistance training. Up until now, it has been proposed that young adults who have an intake of 20 to 25 grams of protein in one meal are maximizing muscle protein synthesis (MPS) and anything beyond this is either being oxidized for energy or passed out through the body in the form of urea.
From a nutritional standpoint, the term “absorption” refers to the passage of nutrients from the gut into the blood. The amount of protein that can be absorbed into the systemic circulation is virtually unlimited. Therefore, absorption appears not to be a limiting factor but more so possibly the potential for amino acid competition at the intestinal wall. Indeed, MPS is known to be capped at an intake of 20 to 25 grams; however, higher protein intakes above this have shown greater muscle gains. But how?
It remains speculative as to why a higher protein intake above 20 to 25 grams in healthy young males may improve anabolic potential. The amino acids may be taken up by other tissues such as the gut. The gut potentially provides an avenue whereby circulating amino acids can be released into the blood again to be used for MPS to further enhance muscle building. However, this warrants further research.
Combining all the latest studies together, researchers suggest that if the primary goal is to build muscle, it's best practice to at least consume protein at a target intake of 0.4 g/kg/meal across a minimum of four meals to reach your protein macros of 1.6 g/kg/day. There appears to be an upper limit at of 2.2 g/kg/day which would necessitate an intake of 0.55 g/kg/meal across five meals. That’s approximately 38.5 grams of protein per meal for a 70 kg (155 lb.) individual. This strategy would maximize acute and chronic anabolic adaptations according to the latest research.
Further research is needed to clarify a specific upper threshold for per-meal protein intake.
Steve O'Mahony BSc MSc
Brad Jon Schoenfeld & Alan Albert Aragon, 2018. How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution. Journal of the International Society of Sports Nutrition 15:10