L-carnitine, also known as L- carnitine or transliteration carnitine, is an amino acid that can promote the transformation of fat into energy. Red meat is the main source of L-carnitine and has no toxic side effects on human body. Different types of daily diets already contain 5- 100 mg of L-carnitine, but the average person can only take 50 mg from the diet every day, and vegetarians take even less. The main physiological function of L-carnitine is to promote the conversion of fat into energy. Taking L-carnitine can reduce body fat and weight without reducing water and muscle. In 2003, it was recognized by the International Obesity and Health Organization as the safest nutritional supplement without side effects.