Although short-term studies have shown that conjugated linoleic acid (CLA) can reduce body fat mass and increase lean mass, the long-term effects of this dietary supplement have not been researched. Now, a study published in the June issue of the American Journal of Clinical Nutrition (2004; 79 [6], 1118–25) has determined that CLA may have long-term effects on reducing body fat in overweight but otherwise healthy adults.

In studying subjects over a 12-month period, the researchers found that those who took 3.4 g of CLA each day for 1 year experienced as much as a 9% reduction in their body fat mass compared to those in the placebo group. Daily caloric intake and exercise were similar for both groups in this randomized, double-blind study. Some scientists believe that CLA decreases fat stores after eating, thereby increasing metabolism and fat breakdown and decreasing the total amount of fat cells.