Effects of a Weight Loss Program on Body Composition and Resting Energy Expenditure according to UCP 2 Genotype in Overweight Subjects

The objective of this study was to examine the effects of a weight loss program on the degree of obesity and levels of resting energy expenditure (REE) in overweight subjects according to their mitochondrial uncoupling protein 2 (UCP 2) genotype. Twenty-three subjects with a body mass index (BMI) greater than 27 were recruited from the Obesity Clinic of the Kyung-Hee University Hospital during the period of December 2000 - August 2001. The subjects were genotyped for the exon 8 allele; 15 subjects were found to be of del/del genotype, 8 were del/ins, and none were of ins/ins genotype. No significant association was found between the different UCP 2 genotypes and the initial levels of weight, fat mass (FM), lean body mess (LBM), BMI, REE, and REE/LBM ratio. After 12 weeks of a weight loss program, body weight and FM were significantly decreased, while LBM, total body water (TBW), and REE were not changed, irrespective of UCP 2 genotype. Initial fasting plasma levels of albumin, glucose, triglyceride, lipoprotein cholesterol, insulin, free triiodo-thyronine (T3), free fatty acid (FFA), and leptin were not different according to the UCP 2 genotype; furthermore, these blood parameters were not changed after the 12-week weight loss program. However, plasma levels of leptin decreased in both the del/del and ins/del genotypes, from 18.7 ng/ml to 13.4 ng/ml (p<.05), and from 18.1 ng/ml to 13.9 ng/ml (p＜.05), respectively, after the weight loss program. In conclusion, this study found no significant association between the del/del or del/ins UCP 2 genotypes and differing levels of REE or differing degrees of obesity, either before or after a weight loss program. This study provided evidence that a well- managed weight loss program could maintain levels of REE, which plays an important role in the maintenance of energy balance.