Conjugated linoleic acid supplementation for 1 y does not prevent weight or body fat regain.

Background: Conjugated linoleic acid (CLA) is marketed as a safe, simple, and effective dietary supplement to promote the loss of body fat and weight. However, most previous studies have been of short duration and inconclusive, and some recent studies have questioned the safety of long-term supplementation with CLA.

Objective: Our aim was to assess the effect of 1-y supplementation with CLA (3.4 g/d) on body weight and body fat regain in moderately obese people.

Design: One hundred twenty-two obese healthy subjects with a body mass index (in kg/m2) > 28 underwent an 8-wk dietary run-in with energy restriction (3300-4200 kJ/d). One hundred one subjects who lost >8% of their initial body weight were subsequently randomly assigned to a 1-y double-blind CLA (3.4 g/d; n = 51) or placebo (olive oil; n = 50) supplementation regime in combination with a modest hypocaloric diet of -1250 kJ/d. The effects of treatment on body composition and safety were assessed with the use of dual-energy X-ray absorptiometry and with blood samples and the incidence of adverse events, respectively.

Results: After 1 y, no significant difference in body weight or body fat regain was observed between the treatments. The CLA group (n = 40) regained a mean (+/-SD) 4.0 +/- 5.6 kg body weight and 2.1 +/- 5.0 kg fat mass compared with a regain of 4.0 +/- 5.0 kg body weight and 2.7 +/- 4.9 kg fat mass in the placebo group (n = 43). No significant differences in reported adverse effects or indexes of insulin resistance were observed, but a significant increase in the number of leukocytes was observed with CLA supplementation.

Conclusion: A 3.4-g daily CLA supplementation for 1 y does not prevent weight or fat mass regain in a healthy obese population.