Association between obesity and femoral neck strength according to age, sex, and fat distribution

Abstract

Summary: Indicators of total and abdominal obesity were negatively associated with femoral neck strength indices. There are age-, sex-, and fat distribution-specific differences in the magnitude of these associations. These suggested that indicators of obesity with different magnitude according to age, sex, and fat distribution associated with poor bone health. Introduction: Fat regulates bone metabolism, but the associations of total and abdominal obesity with bone health are inconsistent. We investigated the association between indicators of obesity and composite indices of femoral neck (FN) strength reflecting the risk of hip fracture. Methods: This population-based cross-sectional study examined data from the Korea National Health and Nutrition Examination Surveys. Participants were divided into groups according to age (25–49/≥50 years) and sex. We examined total fat mass (TFM) and percentage fat mass (pFM) as indicators of total obesity and truncal fat mass (TrFM) as an indicator of abdominal obesity. We calculated the composite indices of FN strength and anthropometric clinical indicators of abdominal obesity. Results: TFM, pFM, and TrFM were negatively associated with the composite indices, irrespective of age and sex (P < 0.001–0.005). Most anthropometric clinical indicators of abdominal obesity showed negative associations with the composite indices regardless of age and sex (P < 0.001–0.048), except for women aged 25–49 years. In men, magnitudes of the negative contributions of TFM to the composite indices were significantly stronger at age 25–49 years than at age ≥50 years. Magnitudes of negative associations of TFM with the composite indices were greater in men than in women. TrFM had a more detrimental effect than TFM on FN strength in men aged 25–49 years and in women of both ages. Conclusion: Indicators of total and abdominal obesity negatively associated with FN strength, and magnitudes of their effects on bone health differed according to age, sex, and fat distribution.