How much protein can your body absorb? Researchers explain
On the other hand, Nelson notes that the number of amino acids to which one can become accustomed stimulate muscle growth2or muscle protein synthesis (MPS) is limited.
He likens the process of muscle hypertrophy (aka muscle building) to an assembly line: a calorie surplus is needed to fuel the line, leucine (a type of branched-chain amino acid) is needed to turn it on through a gene called mTOR and essential amino acids are used as a building material for new muscle tissue.
“A leucine level above 2.5 grams per meal will turn on [mTOR]”, protein and amino acid requirement researcher Don Layman, Ph.D., explains on the mindbodygreen podcast. “If you don’t reach that threshold, your protein intake will be wasted.”
This means that the composition of your food is just as important as the number of grams of protein you get in your daily diet.
There are several other factors that can also affect its amount protein that your body can use for muscle growth1including your age, body type and fitness level.
Interestingly, one 2015 study estimated that the amount of protein needed maximize muscle growth3 was up to 0.4 grams per kilogram of body weight for young men and up to 0.6 grams per kilogram for some older men. For more perspective, this means that a 150-pound male may need 27 to 41 grams (including 2.5 grams of leucine) to maximize hypertrophy, depending on age.
Mary Sabat, MS, RDN, LD, notes that your overall protein needs can be affected by a a wide range of factors4, including your age, level of physical activity, intensity and duration of your workouts, and general health. Learn more about determining your personal protein needs here.