Age-related differences in limb fat-free mass and fat mass in healthy Chinese Adults

Fat mass (FM) and fat-free mass (FFM) are important elements to evaluate nutritional status. The aims of this study were to establish reference values for FM and FFM of limbs, develop percentile distributions and assess age-related regional differences in body composition by multifrequency bioelectrical impedance analyzer (BIA) in healthy adults. A cross-sectional study was conducted on 3419 healthy subjects, 1595 men and 1824 women. Regional FM and FFM were measured by BIA. FM in men remained stable in both upper and lower limbs, with reference values (25-75th percentile) of 1-1.5 kg and 4.9-7.2 kg, respectively. Women's leg FM remained stable with aging (reference values 6.2-7.9 kg), increasing in their arms (0.9-1.5 kg for youngest, 1.3-2.3 kg oldest). The reference values of upper limbs FFM were 5.3-6.2 kg in men and 3.3-3.9 kg in women. Lower limbs FFM decreased with age in both gender: the reference values were 19.5-23.3 kg (men) and 13.8-15.4 kg (women) for 18-30 age group, and 17.3-20 kg and 11.2-13.1 kg, respectively, for 60+ age group. These data provided reference values of FM and FFM in both limbs, enabling the identification of age and gender-related changes in limb composition in healthy Chinese subjects.