The Relationship between Body Fat Percent and Bone Mineral Density in Korean Adolescents: The Fifth Korea National Health and Nutrition Examination Survey (KNHANES V-1), 2010

Background: The relationships of total and regional body fat percent with bone mineral density (BMD) in Korean adolescents were examined using the Fifth Korea National Health and Nutrition Examination Survey (KNHANES V-1), 2010. Methods: Body fat percent at whole body (WBFP), trunk (TBFP), and extremities (both upper and lower extremities fat mass/body weight, EBFP), ratio of trunk fat mass to extremities fat mass (TEFR), and BMD at whole body, total femur, and lumbar spine were measured by dual energy X-ray absorptiometry in a population-based sample of 433 boys and 362 girls, aged 12 to 18 years. The analyses were conducted using linear regression analysis with complex sampling design. Results: After adjusting for confounders such as age, height, weight, serum 25-(OH) vitamin D concentration, energy intake, calcium intake, physical activity, and menarche status for girls, WBFP, TBFP, and EBFP were inversely associated with whole and regional BMD in both sexes (P < 0.05). TEFR was positively associated with whole and regional BMD in boys after adjusting for confounders, while it was negatively associated in girls (P < 0.05). However, the associations were non-significant when bone mass-free lean mass was adjusted instead of bodyweight except for a positive association between TEFR and BMD in boys. Conclusion: In Korean adolescents, total and regional body fat percent is not independently associated with BMD after adjusting for bone mass-free lean mass but higher fat in trunk as compared to extremities may be protective for BMD in boys.