← back to evidence hierarchy
evidence card · bcaa_muscle_building_beyond_protein

BCAA supplementation increases muscle protein synthesis or builds muscle beyond what adequate dietary protein provides

H1 ▽ contradicts stakes low
1 post scored · across 1 account · 2 sources

Summary

When protein intake is adequate, BCAA supplementation does not further stimulate MPS in humans. Isolated leucine/BCAAs in isocaloric/iso-protein designs are null. BCAAs became popular from rat and bolus-feeding studies that don't translate.

Five-score assessment

Scores not yet assigned for this card. (Legacy card; will be populated on next refinement.)

Scope

Population
adults with adequate dietary protein intake (~1.6 g/kg/d)
Intervention
BCAA supplementation
Outcome
muscle protein synthesis, lean mass gain
Not supported for
  • additional effect beyond adequate protein

Evidence sources

Account mentions

  • @BioLayne stance: refutes · alignment: aligned · score 97/100 · 2026-04-13 post ↗