The effect of conjugated linoleic acid supplementation after weight loss on body weight regain, body composition, and resting metabolic rate in overweight subjects

Abstract

OBJECTIVE:To study the effects of 13 weeks conjugated linoleic acid (CLA) supplementation in overweight subjects after weight loss on weight regain, body composition, resting metabolic rate, substrate oxidation, and blood plasma parameters. DESIGN: This study had a double-blind, placebo-controlled randomized design. Subjects were first submitted to a very-lowcalorie diet (VLCD 2.1 MJ/d) for 3 weeks after which they started with the 13-week intervention period. They either received 1.8 g CLA or placebo per day (low dosage, LD) or 3.6 g CLA or placebo per day (high dosage, HD). SUBJECTS: A total of 26 men and 28 women (age 37.877.7 y; body mass index (BMI) 27.871.5 kg/m 2 ). MEASUREMENTS: Before VLCD (t ¼ À3), after VLCD but before CLA or placebo intervention (t ¼ 0) and after 13-week CLA or placebo intervention (t ¼ 13), body weight, body composition (hydrodensitometry and deuterium dilution), resting metabolic rate, substrate oxidation, physical activity, and blood plasma parameters (glucose, insulin, triacylglycerol, free fatty acids, glycerol and b-hydroxy butyrate) were measured. RESULTS: The VLCD significantly lowered body weight (6.971.7%), %body fat, fat mass, fat-free mass, resting metabolic rate, respiratory quotient and plasma glucose, insulin, and triacylglycerol concentrations, while free fatty acids, glycerol and b-hydroxy butyrate concentrations were increased. Multiple regression analysis showed that at the end of the 13-week intervention, CLA did not affect %body weight regain (CLA LD 47.9788.2%, CLA HD 27.4729.8%, Placebo LD 32.0742.8%, Placebo HD 22.5737.9%). The regain of fat-free mass was increased by CLA (LD 6.273.9, HD 4.672.4%) compared to placebo (LD 2.873.2%, HD 3.473.6%), independent of %body weight regain and physical activity. As a consequence of an increased regain of fat-free mass by CLA, resting metabolic rate was increased by CLA (LD 12.0711.4%, HD 13.7714.4%) compared to placebo (LD 9.1711.0%, HD 8.678.5%). Substrate oxidation and blood plasma parameters were not affected by CLA. CONCLUSION: In conclusion, the regain of fat-free mass was favorably, dose-independently affected by a 13-week consumption of 1.8 or 3.6 g CLA/day and consequently increased the resting metabolic rate. However, it did not result in improved body weight maintenance after weight loss.

The role of conjugated linoleic acid in reducing body fat and preventing holiday weight gain

“…7,8,12,13 Berven et al 8 found no significant effect on fat mass with a protocol of 3.4 g/day CLA for 12 weeks, although a trend was observed for body fat to decrease with CLA (0.9 kg) and increase with placebo (0.3 kg). In this study, body composition was assessed with BIA, a method that may be less precise in overweight adults.…”

“…24 In addition, the study length was possibly too short for an effect to be observed. A commonality among the three remaining studies in overweight adults that did not find an effect of CLA on body fat was the inclusion of a weight loss component: Whigham et al 13 included a 12-week very low-calorie diet (VLCD); Kamphius et al 12 utilized a 3-week VLCD; and Atkinson 7 included a diet and exercise regimen during 6 months of treatment. Possibly, the effect of calorie restriction for weight loss in prior studies introduced variability in body weight and body composition change and masked the effect of CLA.…”

“…6 Proposed mechanisms have included increased fat mobilization and oxidation, reduced adipocyte proliferation and differentiation, and increased apoptosis in pre-adipocytes. 6 Despite clear evidence that CLA reduces body fat in animals, the effect of CLA supplementation on body composition in humans has been inconsistent: of seven studies that have evaluated body composition change with mixed-isomer CLA among overweight or obese adults, [7][8][9][10][11][12][13] only three have shown a significant reduction in fat mass. [9][10][11] The conflicting results in human versus animal studies have been attributed to factors such as lower doses per unit body weight; the use of young, growing animals versus adult humans; and the limited sensitivity and accuracy of in vivo body composition measures.…”

Conjugated linoleic acid (CLA) and obesity

“…Published studies report contradicting results. Although in the majority of them there are no significant differences on body weight, body composition 26 or weight regain 27,28 between controls and CLA-supplemented groups, some studies suggest that CLA might have a tendency to increase lean body mass 27,29,30 . On one hand, one study carried out in overweight/obese adult volunteers 30 report a reduction in body fat mass with doses $3.4 g MI-CLA per day at week 12 (150-580 g more than placebo), with a significant increase in body lean mass in the group that received 6.8 g MI-CLA per day, measured by dual-energy X-ray absorptiometry; however, this group was also the only one with a significant increase in exercise level.…”

“…[30][31][32][33] m body lean mass? 27,29,[30][31][32][33] Cis-9,trans-11 CLA m feed efficiency and growth in weanling animals 10,14,[18][19][20] CLA -conjugated linoleic acid. m -increase; k -decrease; ?…”