The available research indicates that a total daily protein intake of 1.6–2.2 grams per kilogram of body weight per day is best to maximize gains in muscle size and strength. But how should one go about consuming this much protein? It appears that multiple protein feedings per day may be best, based on a few lines of evidence.
Muscle protein synthesis (MPS) is a saturable process; that is, ingesting a certain amount of protein at a meal produces a maximal MPS response and ingesting more protein will not further increase MPS. Protein-feeding studies using various doses of whey protein indicate that about 0.24 grams of protein per kilogram of body weight, on average, maximizes the MPS response in young adults, while a dose of 0.40 grams of protein per kilogram of body weight, on average, maximizes the MPS response in older adults.[1]
In addition, the rise in MPS following protein ingestion is transient, and MPS reverts to baseline levels after a few hours.[2][3]
Corresponding with these data, it’s been shown that ingesting 20 grams of whey protein every 3 hours is more effective at stimulating MPS over a 12-hour period than ingesting 10 grams of protein every 1.5 hours or 40 grams of protein every 6 hours.[4]
In similar studies that had two groups consume diets with equivalent amounts of protein but different distribution patterns, one found greater 24-hour MPS rates with a diet that provided 30–33 grams of protein at each main meal, compared to a diet that provided 11, 16, and 63 grams of protein at breakfast, lunch, and dinner, respectively;[5] while the second found that a protein distribution of 0.33, 0.46, and 0.48 grams of protein per kilogram of body weight at breakfast, lunch, and dinner, respectively, was slightly better for increasing lean mass over 12 weeks than a distribution of 0.12, 0.45, and 0.83 grams per kilogram of body weight at breakfast, lunch, and dinner, respectively.[6]
Because muscle gain is ultimately dependent on rates of MPS exceeding rates of muscle protein breakdown over time (see “How does muscle gain occur?” under “What is muscle size and strength?”), it follows that multiple maximal MPS responses per day would be beneficial for muscle gain. This relationship seems to reach a point of diminishing returns, however, as one study in rugby players found no difference between six and four protein feedings per day for increasing lean mass.[7] However, weighing the collective evidence, it’s reasonable to assume that three to four protein feedings per day is superior to one.
Therefore, in the context of a total daily protein intake of 1.6–2.2 grams per kilogram of body weight per day, it’s recommended that individuals consume 0.40–0.55 grams of protein per kilogram of body weight across roughly four meals per day.[8]