The nutritional supplement CLA (conjugated linoleic acid) is a slightly altered form of the essential fatty acid, linoleic acid. Over 200 studies have shown that CLA may play a very important role not only in weight loss, but in helping to fight cancer, diabetes, and atherosclerosis (hardening of the arteries). In promoting weight less double-blind studies show an increase in lean muscle mass and a decrease in percentage body fat compared to placebo group. Researchers believe that CLA helps block fat cells that are in the body from filling up with fat by interfering with a fat-storing enzyme known as lipoprotein lipase as well as by increasing the sensitivity of cells to the hormone insulin. CLA is also believed to help burn fat by revving up muscle metabolism and helping increase lean muscle mass.