Basal metabolic rate and body composition in elderly Indian males

Aging is associated with a decline in basal metabolic rate (BMR) and total energy expenditure. The extent to which changes in fat free mass (FFM) alone, explains the reduction in BMR is still unresolved. In this study, we documented changes in body composition and evaluated its contribution to measured BMR in young and elderly Indian subjects. We compared 16 healthy elderly male subjects in the age group of 60-75 years with 16 Body Mass Index (kg/m2) matched controls in the age group of 18-25 years. Body composition measurements were determined by using multiple skinfolds and bio-impedence method. BMR measured by indirect calorimetry. The % fat and fat free mass was significantly different between two groups. There were significant difference in BMR between elderly and control group (elderly, 5.91 +/- 0.54 vs control; 7.08 +/- 0.65 MJ/day, P < 0.001), which disappeared when corrected for FFM. This suggests that the age related decrease in the BMR is related to the absolute decrease in the FFM in the elderly without any change in the metabolic activity per kg FFM.