The Postprandial Thermic Effects of Diet Induced Thermogenesis in Congenic Lean and Obese LA/Ntul//-Cp Rats

This study provides important new insights and pathways to understand and investigate thermogenic effects of diet and diet induced thermogenesis and their potential contributions to mechanisms of energy balance. 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. The goal of this study was to see how thermic reactions to diet and environment differed in young, middle-aged, and elderly obese rats. Resting oxygen consumption decreased with age, and thermic responses in fat rats were lower than predicted compared to lean rats and are consistent with impairments in both sympathetically mediated and non-sympathetically mediated contributions to the process of non-shivering thermogenesis.