Plasma leucine (A), phenylalanine (B) and threonine (C) concentrations following ingestion of either 20 or 40 g of whey protein isolate in both the lower lean body mass (LLBM) and higher lean body mass (HLBM) groups. Plasma leucine (A), phenylalanine (B) and threonine (C) concentrations following ingestion of either 20 or 40 g of whey protein isolate in both the lower lean body mass (LLBM) and higher lean body mass (HLBM) groups. Data presented as means with 95% confidence intervals. *Significant difference between doses; #significant difference between groups; $significant difference between doses in LLBM group only (all P < 0.05). Lindsay S. Macnaughton et al. PHY2 2016;4:e12893 ©2016 by American Physiological Society