It’s a commonly held belief that the human body can only absorb and utilize about 20-25 grams of protein at one sitting. The absorption part of this idea is clearly false, as our G.I. tract is more than capable of digesting and processing any amount of food that we throw at it. The second part – namely, how much can be effectively utilized for muscle recovery and rebuilding – is less clear. Thankfully, new research is beginning to shed more light on this topic.
In a recent investigation, scientists subjected 30 young resistance-trained men to two full body workouts followed by protein shakes to determine the effect that different dosages had on muscle protein synthesis (MPS). After one of the workouts the men received 20 g of whey protein; upon completion of the second workout, they got a 40 g whey protein shake. Muscle biopsies were taken from all of the men 0, 180, and 300 minutes after each workout.
The findings are not only interesting, but have important implications for lifters. First, 40 grams of protein was shown to have a significantly greater effect on muscle protein synthesis than 20 g the whey shake. Second, the amount of lean body mass (LBM) the men possessed did not appear to influence the dose of whey protein required. Lastly, at least based upon this study, the overall amount of muscle tissue activated during exercise seems to be the most important determinant of the protein required to stimulate max protein synthesis. Whereas lower protein doses may be suitable for localized training, greater amounts of protein were needed to maximize the MPS response to the total body workouts used in this particular study.
The Take Away: The total amount of muscle tissue activated during a workout influences how much protein your body requires for maximum muscle protein synthesis. 20-25 g after training arms, or shoulders, or abs is probably sufficient. But bigger muscle groups and workouts that involve multiple body parts could benefit from heftier protein dosages. If your gains seem to have slowed — or worse, plateaued — try increasing the amount of protein consumed in your post-workout shake.