Q. What is conjugated linoleic acid, and can it really help me lose weight?

A. Conjugated linoleic acid (CLA) is a naturally occurring fat found in the meat of grass-fed animals such as sheep and cattle. The highest concentration of CLA is found in kangaroo meat. Human beings produce some CLA in their bodies as well.

CLA has recently become a popular weight-loss supplement. A number of studies show that it can reduce body fat, especially abdominal fat, while preserving lean muscle mass.

One study, published in the British Journal of Nutrition in March 2007, looked at the ability of CLA to reduce body fat in 118 overweight people. The study was a randomized, double-blind intervention trial; some people were given 3.4 grams of CLA a day, and some were not. Those who took CLA over a six-month period lost 3.4 percent body fat mass; those who didn't take CLA lost only 0.1 percent. When the researchers analyzed only the subjects who most consistently took the CLA, body fat mass losses increased to 5.6 percent - a significant amount of weight loss for those who struggle to lose weight.

Interestingly, study subjects who took CLA showed a decrease in waist size of 2.7 percent (the equivalent of more than an inch), as compared to those who didn't take CLA. It is well known that increased waist size is associated with a number of chronic health conditions such as heart disease, insulin resistance and diabetes.

Another study, published in The European Journal of Clinical Nutrition in October 2003, found that overweight individuals who took CLA for 13 weeks, after following a three-week low-calorie diet, had increased feelings of fullness and satiety and decreased feelings of hunger compared to the placebo group. However, CLA did not improve the ability of the test subjects to keep body weight off.

A study in the Journal of Nutrition in April 2005 found that 3.4 grams of CLA supplementation for two years in overweight adults decreased body fat mass, lowered total cholesterol, reduced LDL cholesterol, and helped maintain weight loss over the long term.

How can you increase your level of CLA naturally? It appears that eating an organic diet may be an important factor. A study published in the British Journal of Nutrition in April 2007 showed that when women in the Netherlands changed from eating non- organic meat and dairy foods to eating organic meat and dairy foods they had a statistically significant increase in CLA in their breast milk.