If you're putting in the work but the scale isn't moving, your body might just need a little help tapping into its fat stores. That's where L Carnitine comes in. It's not a L carnitine is an amino acid that is produced in your body that helps the body turn fat into energy. Carnitine is found in nearly all cells of the body and researchers have Carnitine: Genetic Variants Affecting Mitochondrial Energy and Health Steel Burn When to take L carnitine: Dosage, forms, and side effects