Resting metabolic rate in preadolescent girls at high risk of obesity

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

Cross-sectional study.

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).

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

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.

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.