L-Carnitine 5000L Carnitine is regarded as a top supplement that any exerciser on a training program should incorporate into their diet. This naturally occurring amino acid plays vital roles in fat metabolism, allowing the body to burn more of its fat stores, save more glycogen, and ultimately boost stamina and endurance naturally. Taking L Carnitine 5000 before a workout results in maximum fat burning and a higher metabolic rate, as well as increased energy.