L CARNITINE increases muscle mass, reduces fat mass. Bangkok Hospital Headquarter Targeting Skeletal Muscle Dysfunction With L Carnitine for the Treatment of Patients With Chronic Obstructive Pulmonary Disease In Vivo Acetyl L Carnitine VS L Carnitine: Which is Better? Ingredient Spotlight: L Carnitine Source: Biosynthesised in the body from the amino acids Lysine and Methionine, L Carnitine is a conditionally essential nutrient involved in energy metabolism and fat transport. Key Benefits