Conjugated linoleic acid supplementation in humans: Effects on body composition and energy expenditure

Recent animal studies have demonstrated that dietary conjugated linoleic ac id (CLA) reduces body fat and that this decrease may be due to a change in energy expenditure. The present study examined the effect of CLA supplement ation on body composition and energy expenditure in healthy, adult women. S eventeen women were fed either a CLA capsule (3 g/d) or a sunflower oil pla cebo for 64 d following a baseline period of 30 d. The subjects were confin ed to a metabolic suite for the entire 94 d study where diet and activity w ere controlled and held constant. Change in fat-free mass, fat mass, and pe rcentage body fat were unaffected by CLA supplementation (0.18 +/- 0.33 vs. 0.09 +/- 0.35 kg; 0.01 +/- 0.64 vs. -0.19 +/- 0.53 kg; 0.05 +/- 0.62 vs. - 0.67 +/- 0.51%, placebo vs. CLA, respectively). Likewise, body weight was n ot significantly different in the placebo vs. the CLA group (0.48 +/- 0.55 vs. -0.24 +/- 0.46 kg change). Energy expenditure (kcal/min), fat oxidation , and respiratory exchange ratio were measured once during the baseline per iod and during weeks 4 and 8 of the intervention period. At all three times , measurements were taken while resting and walking. CLA had no significant effect on energy expenditure, fat oxidation, or respiratory exchange ratio at rest or during exercise. When dietary intake was controlled, 64 d of CL A supplementation at 3 g/d had no significant effect on body composition or energy expenditure in adult women, which contrasts with previous findings in animals.