Vitacost Acetyl L Carnitine HCl 500 mg 120 Capsules Acetyl L Carnitine vs L Carnitine: 4 Key Differences Momentous L Carnitine plays an important role in the larger metabolism equation: helping your body use fat efficiently as fuel. Learn more about the science on this week's post on The Wellness Edit. Supplements don't replace the workbut they can support it L Carnitine helps your body turn fat into usable energy, so you can push harder and recover better. Consistency first. Supplements second. Results