By Nashville personal trainer Dan DeFigio

Dietary supplements for fat loss are usually a waste of money. There are a few worthwhile products on the market, however, and L-carnitine may be one of them. L-carnitine controls fat use because it transports fatty acids into the mitochondria of the muscle cells to be burned as fuel. Supplementing with oral carnitine will increase muscle carnitine levels and insure maximum fat burning potential.

Nutrition textbooks will tell you that carnitine is made by the body, making supplementation unnecessary. A sedentary person on a decent diet doesn’t need a carnitine supplement. Active people, however, repeatedly put their bodies in a state of stress that uses lots of carnitine, easily exceeding the body’s ability to make it.(1,2) Athletes will supplement with up to 4 grams daily. Carnitine should be taken at least one hour before exercise.

Some other ergogenic benefits: Carnitine inhibits lactic acid buildup in muscle, it aids in the oxidation of pyruvate and branched chain amino acids in the energy cycle(3), thus increasing endurance and delaying fatigue, and it prevents the buildup of complexes that destabilize muscle membranes.(4) Carnitine increases maximum use of oxygen,(5,6) and reduces post-exercise levels of pyruvate and lactate.(2)

Acetyl l-carnitine also has neuro-protective effects on the brain.

*Note: Stay away from dl-carnitine or racemic carnitine, which are toxic compounds that cause l-carnitine deficiency. Use only the l-carnitine form from reputable companies.

  1. Lennon, et al. Effects of acute moderate-intensity exercise on carnitine metabolism in men and women. Jour. Appl. Physiol. 1983;55:489.
  2. Siliprandi, et al. Metabolic changes induced by maximal exercise in human subjects following l-carnitine administration. Biochem Biophys Acta 1990;1034:17-21.
  3. Bremer J. Carnitine metabolism and function. Physiol. Review 1983;63:1420-1480.
  4. Stumpf DA. Carnitine deficiency organic acidemias and Reye’s syndrome. Neurology 1985;35:1041-1045.
  5. Marconi C, et al. Effects of l-carnitine loading on the aerobic and anaerobic performance of endurance athletes. Eur J Applied Physiol 1985;54:131-135.
  6. Angeline C, et al. Clinical study of efficacy of l-carnitine and metabolic observations in exercise physiololgy. Clinical Aspects of Human Carnitine

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