Branched-Chain Amino Acids (BCAAs, including leucine, isoleucine, and valine) regulate multiple cellular functions as nutrient signaling. For example, BCAAs regulate insulin and glucagon secretion and thus glucose metabolism1. BCAAs, especially leucine, is one key regulator of mTOR signaling, which is the central component of a complex signaling network of insulin signaling, cell growth, and proliferation. BCAAs also regulate protein synthesis and degradation in various tissues.