Evidence Level
The case for EAAs over BCAAs was settled by a pivotal 2017 study by Jackman et al. in Frontiers in Physiology, which found that BCAAs alone stimulated MPS by only 22% compared to rest, whereas a complete EAA profile (or whey protein providing all EAAs) increased MPS by 50%. This is because muscle protein synthesis requires all nine essential amino acids — providing only three creates a bottleneck. A 2018 systematic review by Wolfe confirmed that the anabolic response to amino acid supplementation is maximized only when all EAAs are present. For older adults, Paddon-Jones et al. showed that 6.7g of EAAs stimulated MPS in elderly subjects comparably to 20g of intact protein, suggesting EAAs are particularly efficient for populations with reduced appetite or protein digestion capacity.