Eating protein after working out doesn't change most amino acid levels in your muscles, but it does increase the levels of branched-chain amino acids like leucine, especially with bigger protein meals.
Scientific Claim
The ingestion of protein after resistance exercise does not significantly affect muscle free amino acid concentrations in healthy young men, except for branched-chain amino acids which increase with higher protein doses.
Source Excerpt
“Muscle tissue free phenylalanine concentrations (the amino acid used for the assessment of whole-body amino acid metabolism) did not differ between treatments (Figure 3A). In contrast to the clear dose-response increase in plasma total amino acid concentrations, muscle tissue free amino acid concentrations were not impacted by protein ingestion (Figure 3J). An exception to this pattern were the branched-chain amino acids leucine (Figure 3B), isoleucine, and valine, which were significantly higher in 100PRO over the entire 12-h postprandial period when compared to 25PRO or 0PRO (Figure S2).”
Evidence from Studies
Supporting Studies
The anabolic response to protein ingestion during recovery from exercise has no upper limit in magnitude and duration in vivo in humans
The study measured muscle free amino acid concentrations and found no significant changes for most amino acids, but did observe increases in branched-chain amino acids (leucine, isoleucine, valine) with higher protein doses.