The three BCAAs, leucine, valine, and isoleucine, promote muscle synthesis and are burned by muscles as fuel during a workout. Leucine is most important because it triggers protein synthesis and supports lean muscle mass. Both blood and muscle levels of BCAAs decrease during exercise, which necessitates replenishment to maintain lean muscle mass. Take BCAA+G™ during and/or after exercise to maintain metabolic rate and prevent muscle wasting.