Studies have reported contradictory findings regarding the effect of a mixture of 2 conjugated linoleic acid (CLA) isomers on body weight and some serum indices. This study aims to investigate the effect of daily supplementation of these 2 isomers on body composition and serum leptin and insulin levels in obese adults.This randomized, double-blind clinical trial was performed on 54 adults with class I obesity. The subjects were randomly assigned into 2 groups of 27 and were followed for 3 months so that a total of 3000 mg of CLA supplement and placebo were administered in 3 daily doses in the intervention and control groups, respectively. Body composition indices as well as fasting serum levels of insulin and leptin were also measured. The paired t-test was used for evaluating within-group effects from baseline. The independent t-test was used to compare between-group differences for variables with normal distribution.Although body weight and body mass index (BMI) were not significantly decreased during intervention in groups, but the body fat mass (BFM) (P=0.034), body fat percentage (P=0.022) and trunk fat (P=0.027) decreased significantly during intervention with CLA. The fasting plasma sugar (P=0.042) and Homeostatic model assessment for insulin resistance (HOMA/IR) (P=0.044) in the intervention group declined during 12 weeks of intervention. Serum leptin was associated with a significant decrease during the intervention period (P=0.039).CLA supplementation could reduce body fat and serum leptin. Hence, it could be taken into account as a factor for weight loss but not to control or prevent diabetes.
