The Benefits (and Limitations) of L Carnitine for Fat Loss L carnitine is a naturally occurring amino acid structure that is made in the human brain, liver, and kidneys. L carnitine plays a critical role in energy production, as it converts fat into energy. L CARNITINE increases muscle mass, reduces fat mass. Bangkok Hospital Headquarter New study links L carnitine in red meat to heart disease Harvard Health L Carnitine Benefits for Chronic Fatigue Syndrome