BACKGROUND AND AIMS: Loss of muscle mass and gain of adipose tissue are hallmarks of aging among men in western populations. However, the extent to which these changes reflect inherent senescence is unclear. To determine age-related patterns of body composition and testosterone (T) among men in a subsistence population we sampled 104 nomadic and 102 settled men, ages 20+ years, among the Ariaal of northern Kenya. METHODS: Anthropometric measures included height, weight, skinfolds, and waist circumference. Saliva samples, collected in the morning and afternoon, were assayed for T. Results were analyzed using general linear models, based on 10 year age groups. RESULTS: Average overall BMI was 17.9+/-2.0 kg/m2. Settled and nomadic males did not differ in fat free mass (FFM). FFM peaked in the 30s with a significant decline in the oldest age group. Percent body fat and waist circumference increased significantly across age groups. Morning mean (+/-SD) salivary T was higher among settled males (107.6+/-57.6 vs 63.4+/-38.1 pmol/L; p<0.001), but did not differ significantly across age groups. Salivary T was positively related to suprailiac skinfolds, percent body fat and waist circumference among the settled males. CONCLUSIONS: Age-related patterns of body composition, but not salivary T, among Ariaal men are consistent with those observed in western populations. Together these results suggest that lower FFM after 60 may reflect senescent processes among human males, while age patterns of adiposity reflect energy balance. T does not appear to play an essential role in age-related patterns of body composition.
BACKGROUND AND AIMS: Loss of muscle mass and gain of adipose tissue are hallmarks of aging among men in western populations. However, the extent to which these changes reflect inherent senescence is unclear. To determine age-related patterns of body composition and testosterone (T) among men in a subsistence population we sampled 104 nomadic and 102 settled men, ages 20+ years, among the Ariaal of northern Kenya. METHODS: Anthropometric measures included height, weight, skinfolds, and waist circumference. Saliva samples, collected in the morning and afternoon, were assayed for T. Results were analyzed using general linear models, based on 10 year age groups. RESULTS: Average overall BMI was 17.9+/-2.0 kg/m2. Settled and nomadic males did not differ in fat free mass (FFM). FFM peaked in the 30s with a significant decline in the oldest age group. Percent body fat and waist circumference increased significantly across age groups. Morning mean (+/-SD) salivary T was higher among settled males (107.6+/-57.6 vs 63.4+/-38.1 pmol/L; p<0.001), but did not differ significantly across age groups. Salivary T was positively related to suprailiac skinfolds, percent body fat and waist circumference among the settled males. CONCLUSIONS: Age-related patterns of body composition, but not salivary T, among Ariaal men are consistent with those observed in western populations. Together these results suggest that lower FFM after 60 may reflect senescent processes among human males, while age patterns of adiposity reflect energy balance. T does not appear to play an essential role in age-related patterns of body composition.