Resting metabolic rate in preadolescent girls at high risk of obesity

Abstract

OBJECTIVE: To investigate whether children at high risk of obesity have a reduced resting metabolic rate (RMR).

DESIGN: Cross-sectional study.

SUBJECTS: 93 healthy girls (age: 8–12 y) were allocated to one of four groups, according to the subjects’ and their parents’ weight status: group 1, overweight children with both parents overweight (OB/OB₂; n=17); group 2, normal weight children with both parents overweight (N/OB₂; n=28); group 3, overweight children of discordant parents (OB/OB₁; n=21) and group 4, normal weight children with both parents normal weight (N/OB₀; n=27).

MEASUREMENTS: Weight, height, fat-free mass (FFM) and fat mass (FM) by bioelectrical impedance analysis (BIA), RMR (indirect calorimetry) for the duration of 25 min.

RESULTS: Controlling for disparities in body composition, age and physical maturity, significant differences were found in adjusted group means of RMR (OB/OB₂ 1181 kcal/d; N/OB₂ 1276 kcal/d; OB/OB₁ 1234 kcal/d; N/OB₀ 1199 kcal/d; P<0.02) with the OB/OB₂ girls showing the lowest energy expenditure.

CONCLUSION: We found evidence that preadolescent girls at risk of obesity, are not generally predisposed to a higher body weight, because of a greater metabolic efficiency. In fact, our data show that more emphasis should be laid on defining different subgroups of both overweight and normal weight subjects in studies investigating metabolic rate.