Bone Mineral Content as a Driver of Energy Expenditure in Prepubertal and Early Pubertal Boys.

OBJECTIVE: To examine the associations of bone and bone-secreted factors with measures of energy metabolism in prepubertal and early pubertal boys. STUDY DESIGN: Participants in this cross-sectional, observational study included 37 (69% black, 31% white) boys, aged 7-12 years (Tanner stage

Associations among calcium intake, resting energy expenditure, and body fat in a multiethnic sample of children.

OBJECTIVE: The objective was to determine if calcium intake was associated with resting energy expenditure (REE) and body fat in children after accounting for ancestral genetic background. STUDY DESIGN: Participants included 315 children. REE, body composition, and dietary calcium were assessed by indirect calorimetry, dual-energy x-ray absorptiometry, and 24-hour recalls, respectively. Structural equations modeling assessed the relationships among REE, calcium intake, and body fat. RESULTS: There were positive associations between calcium intake and REE (P<.01) and between REE and total body fat (P<.0001). There was indirect effect of calcium intake on total body fat (P<.01). There were positive associations between calcium intake and REE (P<.01), and a trend toward an association of calcium intake and total body fat (P=.065) among boys only, whereas the only significant relationship among girls was an association of REE on total body fat (P<.0001). CONCLUSIONS: REE was associated with calcium intake and mediated a relationship between calcium intake and total body fat. These findings suggest calcium intake may play a role in fat accumulation and energy balance through its effects on REE, especially in boys.

The role of European genetic admixture in the etiology of the insulin resistance syndrome in children: are the effects mediated by fat accumulation?

OBJECTIVES: To evaluate the contribution of European genetic admixture (EUADM) to insulin resistance syndrome (IRS) in a multiethnic sample of children age 7-12 years, and to explore whether body fat affects this relationship. STUDY DESIGN: Anthropometric measurements and blood pressure were assessed in 243 children. After an overnight fast, an intravenous glucose tolerance test was conducted, and measures of fasting insulin/glucose, lipids, insulin sensitivity (SI), and acute insulin response to glucose (AIRg) were obtained. The proportion of EUADM was determined by maximum likelihood estimation using 140 ancestry informative markers. Subjects were stratified into tertiles according to the proportion of EUADM for analyses. Subjects were categorized as lean or obese using body fat percentage cutpoints (25% in boys, 30% in girls). RESULTS: Among lean subjects (72%), the tertile representing the greatest proportion of EUADM was associated with higher SI (P<.001) and serum glucose (P<.05) and lower insulin (P<.05), AIRg (P<.001), high-density lipoprotein cholesterol (P=.05), and blood pressure (P<.05). However, among obese subjects, EUADM was associated only with SI (P<.05). CONCLUSIONS: Our results suggest that population differences in IRS likely have a genetic component, but that the influence of genetic background may be masked by obesity.