Assessment and relation of total and regional fat mass with bone mineral content among Indian urban adolescents

Background: Fat mass (FM) has been shown to have an effect on bone mass accrual. Though gender and ethnic differences in body composition and bone accrual during puberty have been reported, there are limited data available for Indian children and adolescents. Objective: To generate age and gender based percentile charts of FM among urban Indian children and adolescents and to evaluate the relationship with pubertal status and bone mineral content (BMC). Subjects: There were 1403 children and adolescents (boys: 826; girls: 577) in the study. Methods: Total and regional FM, BMC, and pubertal staging were assessed. Fat mass index (FMI), FM/height ratio and BMC/FM ratio, were calculated. Results: The age of the study population ranged from 5 to 18 years, with a mean age of 13.2 +/- 2.7 years (boys: 13.0 +/- 2.7; girls: 13.4 +/- 2.8 years). Total and regional FM as well as FMI increased with increasing age in both genders. The highest percent increase in mean total FM occurred in the age group >8-11 years and decreased thereafter. The total and regional FM was higher in more advanced stages of pubertal maturation. There was no difference in total and regional FM between genders in prepubertal group. The age and pubertal associated increase in FM was significantly higher in girls than boys (p < 0.0001). Total as well as regional FM and FMI were positively correlated with age, body mass index, total lean mass, and BMC even after adjusting for age, lean mass, and biochemical parameters. Conclusions: Total and regional FM increased with age and pubertal maturation in both genders. FM was positively correlated with BMC.