Lifestyle factors associated with age-related differences in body composition : the Florey Adelaide Male Aging Study

Background: Age-related change in body composition is associated with adverse health outcomes, including functional decline, disability, morbidity, and early mortality. Prevention of age-related changes requires a greater understanding of the associations among age, lifestyle factors, and body composition. Objective: We aimed to comprehensively determine lifestyle factors associated with age-related differences in body composition assessed by using dual-energy X-ray absorptiometry. Design: We analyzed baseline (cross-sectional) data collected from 2002 to 2005 for ≈1200 men in the Florey Adelaide Male Aging Study, a regionally representative cohort of Australian men aged 35-81 y. Results: Mean values for whole-body lean mass (LM) and areal bone mineral density (aBMD) decreased, whereas mean values for abdominal fat mass (FM) and whole-body and abdominal percentage FM (%FM) increased with age. No significant age-related differences were found for whole-body FM. Multiple adjusted odds of being in the highest tertiles for whole-body and abdominal %FM decreased for smokers (63-71%) but increased with age group and for lowest energy (43-50%), carbohydrate (92-107%), and fiber (107%) intake tertiles. Multiple adjusted odds of being in the highest aBMD tertile decreased for lowest body mass (92%) and carbohydrate intake (63%) tertiles and for men aged ≥75 y (78%) but increased for Australian birth (58%) and for participation in vigorous physical activities (82%). Conclusions: Age-related differences in body composition indicate that whole-body FM remains stable but increases viscerally and that whole-body %FM is confounded by LM, whereas aBMD decreases with age. Age-related differences in %FM and aBMD are associated with demographic and lifestyle factors.