Regional percent fat and bone mineral density in Korean adolescents: the Fourth Korea National Health and Nutrition Examination Survey (KNHANES IV-3), 2009.

The effects of total and regional (trunk, arm, and leg) percent fat on total and regional (arm, leg, rib, thoracic spine, lumbar spine, proximal femur, and pelvis) bone mineral density (BMD) in Korean adolescents were examined using the Fourth Korea National Health and Nutrition Examination Survey, 2009. Percent fat and BMD were measured by dual energy X-ray absorptiometry in a population-based sample of 710 Korean adolescents (365 boys and 345 girls), aged 10-19 years. After adjusting for age, height, weight, serum vitamin D, dietary calcium intake, and menarche for girls in complex sampling linear regression analysis, higher total and regional percent fat were associated with low total BMD and BMD in all regions in boys aged 13-16 years, while the associations were inconsistent for early and late adolescent boys. In girls, the inverse associations were more consistent for those aged 17-19 years than for younger girls. While most of total and regional percent fat were negatively associated with BMD of thoracic and lumbar spine and femur in boys, most of these relationships were not significant in girls. The negative association with total BMD was consistent for trunk percent fat but variable for arm and leg percent fat according to age subgroup and gender. In conclusion, the unfavorable effect of regional percent fat on all regional BMD is more consistent in boys aged 13-16 years and in girls aged 17-19 years, while the relationship appears to be gender and age subgroup-specific.