Conjugated linoleic acid (CLA) is quite possibly the supplement of choice when looking for that weight-loss miracle pill. One group of overweight women lost 9% body fat in one year's time even though they didn't change their lifestyle or eating habits in any way. This is the first time CLA has been researched for it's effects on body composition an the results are clearly remarkable. Never heard of CLA? CLA is a naturally occurring fatty acid found in meat and dairy products. It is a popular dietary supplement benefiting people who want to lose fat, maintain weight loss, lower blood pressure, boost their immune system, retain lean muscle mass, and control type 2 diabetes - the type of diabetes that is often associated with obesity. CLA comes in different concentrations. Products containing 80% CLA are recommended to get maximum weight-loss results. CLA has been shown to prevent heart disease and several types of cancer. It also appears to enhance the immune system. One study involving 180 overweight men and women, all between 25 and 30 BMI (body mass index). A BMI -- an indicator of body fat -- over 25 has been linked to an increased risk of heart disease and other medical problems, such as diabetes. The volunteers were mostly female -- 149 women and 31 men. Volunteers were assigned to three groups. The two groups taking CLA got either the typical off-the-shelf pills (4.5 grams of 80% CLA) daily or the syrup formulation (3.6 grams of 76% CLA disguised in a capsule) daily. The third group took a placebo capsule filled with olive oil daily. Participants were not required to change their diet or exercise habits. However, a nurse did give dietary and exercise advice upon request. Daily calorie intake was similar among the three groups; all volunteers reduced their calorie intake a little during the study. All got about the same amount of exercise. This strongly suggests that the observed effects of CLA on body composition were independent of diet. The decreased calorie intake may be partly due to the supplements and/or a reduced appetite. Also, because volunteers kept a food diary, they learned to cut food intake. Several times during the 12-month study period, the study group came to a clinic to have their weight, BMI, and blood checked. They also completed questionnaires on their diet and exercise in the previous two weeks.

At the end of one year:

• Both CLA groups lost weight -- about 4 pounds; the placebo group stayed the same.
• The CLA syrup group had a 9% body fat loss; the CLA pill group had 7% loss; the placebo group had no body fat loss.
• Both CLA groups had similar improvements in muscle mass.

Regarding other risk factors:

• The CLA pill group had slightly higher LDL bad cholesterol.
• The CLA syrup group had slightly lower HDL good cholesterol.
• Both CLA groups had higher lipoprotein levels, a marker of inflammation and heart disease.
• Both CLA groups had higher levels of leptin, a hormone thought to be a heart disease marker.
• Both CLA groups had higher white blood cell counts, which could trigger damaging artery inflammation.
• The CLA groups had only modest changes in blood sugar levels, a marker for diabetes.

The results of this study corroborate and expand on the findings of the previous short-term studies. Results show that the effect is greatest in those with highest body mass index, especially women with a 25 to 30 BMI. As far as the heart disease risk factors, the variations seen in the CLA groups are within normal physiological range. Increased white blood cells may reflect the heightened immune response that other studies have shown. In studies in Holland, CLA has been shown to prevent some viral infections. The mechanism(s) by which CLA decreases body fat mass and increases lean muscle mass is not completely understood. CLA is known to accumulate in tissues of animals and humans where it is readily metabolized. CLA may trigger fat cell death, shrink fat cells, or it may speed up metabolism to promote weight loss.