Amino acids are the building blocks of proteins. Some types are produced in the body while others must be consumed in the diet. Many fat loss supplements are marketed with claims of fat-burning abilities due to amino acid contents, though limited research has supported these claims. However, much of the available information currently shows a relationship between taking amino acid supplements and increasing lean muscle tissue or sports performance, which both can contribute to fat loss when combined with lowered caloric intake.
The amino acid 5-HTP, or 5-Hydroxytryptophan, helps to boost serotonin levels in the brain. Serotonin affects appetite among other things; and if levels are decreased, then overeating can ensue. Though it is not found naturally in foods, its precursor, tryptophan, is present in fowl, dairy products, potatoes and some leafy green vegetables. Studies referenced by the University of Maryland Medical Center have found that taking 5-HTP supplements may lead to a smaller appetite and thus weight loss.
Leucine, valine and soleucine are three types of branched-chain amino acids. A 2004 study led by Shimomura and published in the "Journal of Nutrition" supports the claims that BCAAs are oxidized in skeletal muscle during exercise and that supplementation encourages the building of lean muscle mass and prevents muscle damage. Increasing lean muscle mass in the body leads to increased metabolism, which in turn causes higher levels of fat and calorie burning.
Overweight subjects given an amino acid mixture containing lysine burned more fat during exercise than subjects not taking the supplement, according to a 2010 study by Michishita and published in the "Journal of International Medical Research." Lysine must be obtained from the diet, as the body cannot produce it. It also helps the body to produce carnitine, which lowers cholesterol and converts fatty acids into energy, according to the University of Maryland Medical Center.
Lysine has an inverse relationship with arginine, meaning that higher levels of lysine are present when arginine levels are low; if you are taking arginine supplements, discuss your options with your doctor prior to adding lysine supplements to your diet.
Creatine is another amino acid that is touted in many sports supplements for its muscle-building and energy-creating properties. However, research has produced mixed results when trying to prove these claims. Meanwhile, the University of Maryland Medical Center states that some clinical studies have shown that supplementing with creatine can lead to increased lean muscle mass and improved strength when used during short and intense exercise programs. It is allowed by the National Collegiate Athletic Association (NCAA) and the International Olympic Committee, though schools are not allowed to provide the supplement to athletes. However, high levels of creatine can contribute to kidney damage, and supplementation can cause reduced natural production of the amino acid in the body.