Residual thermic effects of diet induced thermogenesis (RDIT) in aging lean and obese LA/Ntu1//-cp (corpulent) rats

Diet induced thermogenesis has been proposed to account for up to 15% of the caloric content of an ingested meal and to become decreased with aging and in obesity. Genetically obese rodents have been shown to exhibit impairments in the thermic responses to diet and environment, which may partially account for an improved caloric efficiency and to contribute to their increased propensity to become obese. In the present study we sought to determine the thermic responses to diet and environment in aging obese rats when young, middle aged, and aged. Resting oxygen consumption tended to decrease with advancing age and the thermic responses were lower than predicted in obese than in lean rats. This study provides important new insights regarding the thermogenic effects of diet and diet induced thermogenesis and their potential contributions to mechanisms of energy balance across the spectrum of aging in lean and obese LA/Ntul//-cp rats