Longitudinal changes in fatness in white children: no effect of childhood energy expenditure

Area of Science:

• Pediatric Endocrinology
• Human Physiology
• Obesity Research

Background:

• Childhood obesity is a growing concern with unclear etiological factors.
• Reduced energy expenditure is hypothesized to contribute to obesity development.
• Longitudinal data on energy expenditure and childhood adiposity are limited.

Purpose of the Study:

• To investigate the relationship between energy expenditure components and longitudinal changes in body composition in preadolescent children.
• To identify predictors of fat mass accrual during preadolescence.

Main Methods:

• A 4-year longitudinal study of 75 white preadolescent children.
• Annual measurements of body composition and resting energy expenditure (indirect calorimetry).
• Dual measures of total and physical activity-related energy expenditure (doubly labeled water).
• Parental body composition assessed at baseline.
• Hierarchical linear modeling and ANOVA used for analysis.

Main Results:

• The rate of change in fat mass adjusted for fat-free mass was 0.08 kg/y.
• Children with two obese parents showed significantly higher adjusted fat mass gain.
• Greater fat gain was observed in girls compared to boys.
• Initial fatness and parental fatness were significant predictors of fat mass change.
• No component of energy expenditure was inversely related to fat mass change.

Conclusions:

• Sex, initial adiposity, and parental obesity are key predictors of fat mass gain in preadolescence.
• Reduced energy expenditure is not a significant factor in predicting fat mass accrual in this age group.
• Findings challenge the theory that lower energy expenditure directly leads to childhood obesity.