Age-related changes in body composition: a cross-sectional study from a single center in Buenos Aires, Argentina

INTRODUCTION: Several physiological changes occur during the aging process, with perhaps the most apparent being modifications in body composition. The objective was to evaluate ongoing changes in body composition, throughout the aging process. MATERIALS AND METHODS: A cross-sectional study was conducted in 975 participants (612 women, 363 men) aged 18-89 years, whose body composition was assessed using dual-energy X-ray absorptiometry (DXA). RESULTS: The mean age was 48 ± 17 years for women and 43 ±15 years for men (p < 0.01). Men exhibited a greater amount of lean mass compared to women (54.5 ± 9.4 vs. 37.7 ± 5.5 kg; p<0.0001). Women showed a higher percentage of lower limb lean mass than men (78 vs. 74%; p < 0.05). Age was independently associated with decreased appendicular muscle mass, with a reduction of 0.38 kg per decade. On the other hand, women exhibited higher relative fat mass and a greater proportion of lean tissue in the lower limbs. Fat tissue increased with age in both sexes, remaining consistently higher in women. Lean mass and bone mineral content peaked in the second and third decades of life and declined thereafter. CONCLUSION: This study highlights the changes in body composition at various life stages, revealing a peak gain of lean tissue between the second and third decades, followed by a decline in subsequent years. To our knowledge, this is the first study that evaluates the changes in body composition in our country.