-carnitine is an amino acid (a building block for proteins) that is naturally produced in the body.L-carnitine supplements are used to increase L-carnitine levels in people whose natural level of L-carnitine is too low

• L-carnitine is synthesized in the body from the amino acids lysine and methionine. Regardless of what your bodybuilding and fitness goals are, losing fat or gaining muscle, your chances of success will increase greatly if you have l-carnitine in your supplement arsenal. Studies focusing on how carnitine works have been done as far back as 1937.
• It has been established that an adequate supply of l-carnitine is necessary for the maintenance of good health. L-carnitine transports long-chain fatty acids across the mitochondrial membrane to be metabolized.
• L-carnitine was discovered in Russia, and one year later in Germany. The proper name, Carnitine, refers to the Latin origin, (carno, caris). Its structural formula was decoded in 1927, and its physiological significance was understood by the 1960's. L-carnitine is synthesized in the liver and kidneys, from two essential amino acids, lysine and methionine. This synthesis requires the presence of vitamins niacin, B6, and iron. Most (98%) of the carnitine supply resides in the body's muscle tissue. Approximately 80% of the amino acids our bodies need is endogenously synthesized, the remaining 20% are referred to as the essential amino acids. The supply of such aminos, like l-carnitine, must be supplemented exogenously. L-carnitine is available in the following food sources: red meat, diary products, avocado, and tempeh. Although a well balanced diet can provide approximately 75% of what the body is lacking, often conditions arise that make it difficult to obtain all the carnitine one needs.
• If you are looking to get lean, then this is the amino acid you need. L-carnitine transfers long-chain fatty acids, such as triglycerides into mitochondria, where they may be oxidized to produce energy. Carnitine has also been shown to reduce fatigue and serve as an appetite suppressant as well. Therefore, l-carnitine would be a major asset to have in your arsenal when you are dieting. It not only will help keep your body from storing fat, but it will increase your aerobic capacity to help you burn more calories

Minus L-carnitine, fatty acids would have a difficult time permeating the walls of the mitochondria. Energy, stored in carbohydrates and fats, is required to work the muscle. Carbohydrates are converted from glucose to glycogen, to be stored in liver and muscle cells. Eventually, the body turns to fat storage for energy, and possibly, with more ease in the presence of L-carnitine. This is where L-carnitine as a supplement enters. During high energy output, the supply of L-carnitine becomes exhausted. Is it possible to compensate for this decrease solely through metabolic processes and diet? Or is an additional carnitine supplement needed for the extra boost? Judging from the variety of carnitine products now on the market, apparently many believe an additional outside source proves beneficial.