The BCAAs leucine, isoleucine, and valine have assumed particular prominence, both because of their role in affecting mammalian target of rapamycin (mTOR)-key pathways linking nutrition with health and aging (24) and also because their circulating levels are positively associated with obesity, insulin resistance, and metabolic dysfunction in rodents and humans (16, 25, 26). The gene discussed is MTOR; the disease is obesity disorder.