Conjugated linoleic acid reduces body fat and prevents seasonal weight gain among overweight adults

Conjugated linoleic acid (CLA) supplementation has been shown to reduce fat mass in animals, but results in humans have been inconsistent. To further test the effect of CLA on body composition, we conducted a randomized, double‐blind study in 40 overweight adults. For six months including the holiday season, 22 subjects took 3.2 g/d of a 50:50 mixture of cis‐9, trans‐11 and trans‐10, cis‐12 isomers of CLA and 18 subjects took a safflower oil placebo. Using the 4‐compartment model, we found a decrease in body fat with CLA (P = 0.02): while CLA reduced body fat (1.0 ± 2.2 kg, P = 0.05), placebo tended to increase (0.7 ± 3.0 kg, P = NS). CLA also reduced body weight vs. placebo (P = 0.04). Specifically, CLA attenuated weight gain during the holiday season (P = 0.01). To compare our results with previous studies, we performed a meta‐analysis on the rate of fat loss with CLA vs. placebo, which averaged −80 g/wk (P = 0.01). Power analysis indicated that most studies reporting no significant effect of CLA on fat mass were underpowered or of insufficient duration. In conclusion, CLA reduced body fat over six months and prevented weight gain during the holiday season in overweight adults. Research has shown that holiday weight gain contributes to annual weight gain and that overweight individuals are susceptible to greater holiday gains. CLA may aid in reducing these gains, particularly among overweight individuals. Supported by Cognis Co.