Energy expenditure and physical fitness in overweight vs non-overweight prepubertal girls

Abstract

OBJECTIVE: To determine whether overweight children have lower physical activity energy expenditure (EE) and fitness levels than non-overweight children.

STUDY DESIGN: Twenty-four healthy girls aged 7–10 y were divided into overweight (>95th percentile weight-for-height) and non-overweight (10–90th percentile) groups. Basal metabolic rate (BMR), sleeping metabolic rate (SMR), 24 h sedentary EE (SEE) and total EE (TEE) were measured by room respiration calorimetry and doubly labelled water. Physical activity EE and physical activity level (PAL) were calculated. Fitness (VO₂peak) was measured by a treadmill exercise test.

RESULTS: The overweight group had significantly higher body weight, percent fat, fat mass and fat-free mass (FFM) (P<0.001). The overweight girls had higher BMR, SMR, SEE and TEE (P<0.001), but not after adjustment for FFM. Physical activity EE and PAL were not significantly different between groups. After adjusting for FFM or weight, submaximal and peak VO₂ were not significantly different between groups.

CONCLUSIONS: We conclude that these overweight girls do not have lower physical activity EE or fitness levels than the non-overweight prepubertal girls, however, the rather high body fat of the non-overweight group may have precluded us from finding any differences between groups.