Age And Sex Differences In Body Fat And Fat-free Mass: A Cross-sectional Study

Fardib Mahbub, John Akanbi, Stella L. Volpe, FACSM. Virginia Polytechnic Institute and State University, Blacksburg, VA. (Sponsor: Stella L. Volpe, FACSM) BACKGROUND: Women generally have higher percent body fat (%BF) than men, and body fat tends to increase with age. Men generally have higher lean body mass (LBM) than women; however, LBM tends to decrease with age. PURPOSE: We evaluated body composition in recreationally active women and men. We also compared body composition across three age groups. METHODS: In this cross-sectional study, we assessed body composition (%BF, lean body mass [LBM], fat mass [FM], bone mineral density [BMD]) in recreationally active women and men using Lunar iDXA2, MTY dual energy X-ray absorptiometer (DXA). RESULTS: We included 48 recreationally active women (n = 22) and men (n = 26), 51.7 ± 5.7 years of age, in our cross-sectional study. We evaluated them into three different age groups: 40 to 50 years of age, 51 to 55 years of age, and 56 to 65 years of age. We found a significant (p = 0.001) relationship between %BF and sex; women had a higher %BF compared to men (33.15 ± 5.0% vs 22.3 ± 6.0%, respectively). We did not find any relationship between %BF and age (28.7 ± 6.0%, 29.2 ± 8.3%, 26.2 ± 9.0%; p = 0.55, respectively among the three age groups). Women had a higher FM than men (20.6 ± 4.1 kg vs 18.43 ± 6.12 kg; p = 0.14, respectively), but this was not significant. Men had a significantly higher FFM compared to women (62.9 ± 7.0 kg vs 41.36 ± 4.35 kg; p = 0.001, respectively). Those who were 40 to 50 years of age had the highest FM (21.23 ± 4.5 kg), followed by those 51 to 55 years of age (19.3 ± 5.3 kg), followed by those 56 to 65 years of age (17.8 ± 5.2 kg), with no significant difference among the groups (p = 0.47). There were no significant differences (p = 0.81) in LBM FFM among the three age groups (54.03 ± 12.4 kg, 48.1 ± 12.63 kg, and 51.6 ± 11.6 kg, respectively). CONCLUSION: We found that women had a higher %BF and lower LBM compared to men. We found no significant differences in body composition among all the age groups. Future prospective studies on body composition need to be conducted in recreationally active older adults. This study was funded by the American Pistachio Growers Supported by: We acknowledge and thank "American Pistachios Growers" for funding this study