L-Carnitine Tartrate Shown to Fuel Metabolism Stimulant Free Dietary Supplement L-Carnitine: The Science L-Carnitine is a naturally occurring amino acid that plays an essential role in converting fat into a usable energy source. By enabling the body to use that energy as fuel, L-Carnitine supplementation promotes increased metabolism. Key Benefits of L-Carnitine: Shown to Fuel Metabolism Helps Convert Fat into Energy Helps Delay Onset of Muscle Soreness Stimulant Free