Eating protein after working out doesn't change most amino acid levels in your muscles - only the branched-chain amino acids like leucine increase with bigger protein meals.
Scientific Claim
The ingestion of protein after resistance exercise does not significantly affect muscle tissue free amino acid concentrations for most amino acids in healthy young men.
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).”
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, indicating that protein ingestion primarily affects plasma amino acid levels rather than muscle free amino acid pools.