The role of carnitine in normal and altered fatty acid metabolism ScienceDirect From brain to muscle, L Carnitine plays a key role in energy metabolism, endurance, and recovery by supporting efficient fat to energy conversion. Effects and mechanism of L Carnitine on weight loss Meet L Carnitine a naturally occurring amino acid that plays a key role in helping the body convert fat into usable energy. It works by transporting fatty acids into your cells to Carnitine: the claims and why it may not work