The relationships of age, body composition, and physical conditioning status to glucose tolerance, insulin, and lipoprotein levels were examined in 77 healthy, nonsmoking white male volunteers, aged 46 to 73 years with no evidence of coronary artery or endocrine-metabolic disease. The men had a wide range of body fat (13% to 39%), indexed as waist-to-hip ratio (WHR, 0.84 to 1.08), and maximal aerobic capacity (V̇O2max, 17 to 48 mL/kg · min). Multiple regression analysis with age, V̇O2max, WHR, and percent body fat as independent variables demonstrated that fasting plasma insulin, triglyceride (TG), and high density lipoprotein cholesterol (HDL-C) levels were independently related to both percent body fat and WHR. In contrast, fasting plasma glucose levels and insulin responses during oral glucose tolerance tests (OGTT) correlated independently with percent body fat, and glucose responses to OGTT correlated only with WHR. Although fasting plasma TG and HDL-C correlated with glucose and insulin levels, in multiple regression analyses only percent body fat and WHR were the significant independent variables. Fasting total and low density lipoprotein cholesterol values were not related to these variables. To test the effects of weight loss and exercise training on these relationships, 20 obese men of comparable age, percent body fat, WHR, and V̇O2max were randomly assigned to weight loss or aerobic exercise training programs. A 12% ± 3% loss in body weight (P < .01, mean ± SD) resulted in a 19% ± 9% decline in body fat (P < .01) with no change in fat free mass, WHR, or V̇O2max. This was associated with significant improvements in lipoprotein lipid profiles, glucose tolerance, and insulin levels. Exercise training raised V̇O2max by 35% ± 22% (P < .001) without significant altering in percent body fat, WHR, lipoprotein lipids, or glucose tolerance; however, insulin levels increased slightly. Collectively, the cross-sectional and longitudinal results support each other and suggest that in older men, percent body fat and WHR are more important determinants of lipoprotein lipid profiles, insulin levels, and glucose tolerance than V̇O2max or age.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism