RESTING METABOLIC RATE AND RESPIRATORY QUOTIENT IN HUMAN LONGEVITY

Significant changes in body composition, body fat distribu-tion, and resting metabolic rate (RMR) occur with aging. In-terestingly, studies on human longevity pointed out that long-lived subjects are less prone to the anthropometrics and metabolic derangement normally observed in the elderly. In-deed, the relationship between energy expenditure and lon-gevity has been poorly investigated. Thus, energy expendi-ture parameters of 28 long-lived subjects were assessed and compared with those of 26 adults and 27 younger elderly. All subjects enrolled were female. In the whole population, RMR was negatively correlated with age ( P < 0.05), waist to hip ratio (WHR) ( P < 0.001), fat mass (P < 0.001), and percent body fat (P < 0.03); respiratory quotient (Rq) displayed an age-related decrease (P < 0.001) and was negatively correlated with WHR ( P < 0.001) and fat-free mass (FFM) (P < 0.006). In multivariate analysis, both RMR and Rq had FFM, WHR, but not body mass index as significant and independent determinants. Splitting the whole study group into subgroups according to age, long-lived subjects had oxygen volume, carbon dioxide volume, and Rq significantly higher than aged subjects but lower than adult subjects. In addition, long-lived subjects had total volume of expired air and RMR greater than aged subjects but not dif-ferent from ones found in adults. In long-lived subjects, Rq was negatively correlated with percent body fat (P < 0.02), plasma glucose (P < 0.05), free fatty acid (P < 0.05), and WHR (P < 0.05), whereas RMR was negatively correlated with WHR (P < 0.05). No significant associations of RMR and Rq with FFM were found. In conclusion, our data demonstrate that human longevity seems protected toward an age-related de-cline. It is likely that the lack of the anthropometrics derange-ment may preserve long-lived subjects from the age-related decrease in energy metabolism.