For over 20 years, studies of CLA (conjugated linoleic acid) have shown that this fatty acid may actually help to reduce abdominal body fat while preserving lean muscle.[1,2,3] CLA is found in animal fats like cream, butter, and the fat marbling of grass-fed beef and lamb, as well as in vegetable oils such as safflower oil.
CLA acts by inhibiting lipoprotein lipase, an enzyme that breaks down dietary fats and enables fat to be stored in the body. CLA decreases the amount of fat that ends up stored in the abdomen by reducing the amount of fat that is broken down. CLA nutritional supplements are being promoted as a magic bullet to reduce body fat, to burn calories more efficiently, and to increase the percentage of lean muscle mass.
Realistically, taking one pill per day is not likely to make you thinner and leaner. If you are overweight, you need to evaluate your complete diet and exercise program. You can lose one pound every 12 days simply by cutting 300 Calories per day from your diet. Exercise will build up your muscles and increase your strength.
 Brown JM, McIntosh MK., Conjugated linoleic acid in humans: regulation of adiposity and insulin sensitivity. J Nutr. 2003 Oct;133(10):3041-6. PMID: 14519781
 Gaullier JM, Halse J, Høye K, Kristiansen K, Fagertun H, Vik H, Gudmundsen O., Supplementation with conjugated linoleic acid for 24 months is well tolerated by and reduces body fat mass in healthy, overweight humans. J Nutr. 2005 Apr;135(4):778-84. PMID: 15795434
 Risérus U, Berglund L, Vessby B., Conjugated linoleic acid (CLA) reduced abdominal adipose tissue in obese middle-aged men with signs of the metabolic syndrome: a randomised controlled trial. Int J Obes Relat Metab Disord. 2001 Aug;25(8):1129-35. PMID: 11477497