RESTING METABOLIC-RATE IN PREADOLESCENT GIRLS AT HIGH-RISK OF OBESITY

OBJECTIVE: To investigate whether children at high risk of obesity hav e a reduced resting metabolic rate (RMR). DESIGN: Cross-sectional stud y. SUBJECTS: 93 healthy girls (age: 8-12 y) were allocated to one of f our groups, according to the subjects' and their parents' weight statu s: 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 (O B/OB1; n = 21) and group 4, normal weight children with both parents n ormal weight (N/OB0; n = 27). MEASUREMENTS: Weight, height, fat-free m ass (FFM) and fat mass (FM) by bioelectrical impedance analysis (BIA), RMR (indirect calorimetry) for the duration of 25 min. RESULTS: Contr olling 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/OB, 1234 kcal/d; N/OB0 1199 kc al/d; P < 0.02) with the OB/OB2 girls showing the lowest energy expend iture. CONCLUSION: We found evidence that preadolescent girls at risk of obesity, are not generally predisposed to a higher body weight, bec ause of a greater metabolic efficiency. In fact, our data show that mo re emphasis should be laid on defining different subgroups of both ove rweight and normal weight subjects in studies investigating metabolic rate.