Lean Body Mass and Bone Health in Urban Adolescents From Northern India

Objective: To prepare percentile charts of lean body mass (LBM) among Indian urban children and adolescents; and to evaluate gender differences in LBM, and its relation with pubertal status. Design: Secondary data analysis. Setting: School in city of Delhi, India. Participants: 1403 apparently healthy children and adolescents (826 boys) with mean (SD) age 13.2 (2.7) years. Outcome measures: Lean body mass assessed by dual energy absorptiometry. Results: Total and regional lean mass were greater in older age groups in both sexes. LBM showed rising trends up to the age of 18 years in boys, whereas it plateaued after the age of 15 years in girls. The age-associated increase in LBM was significantly higher in boys (130%) compared to girls (83%) (P< 0.001). Total and regional lean mass increased with progression of pubertal staging in both genders. During pubertal development, LBM almost doubled (100% increase) from stage-2 to stage-5 in boys, as opposed to a 73% rise in girls (P< 0.001). Total and regional lean mass and Appendicular skeletal muscle mass index (ASMI) was positively correlated with age, body mass index (BMI), serum 25(OH)D, total fat mass, and bone mineral content (BMC). Relation between LBM and BMC remained significant even after adjusting for age, fat mass and various biochemical parameters. Conclusions: Total and regional LBM rise with age and pubertal maturation in both genders, but more so in boys when compared to girls. LBM has direct bearing on BMC even after adjusting for age, fat mass and biochemical parameters.