R13 Body Weight, Adiposity, Energetics and Longevity: Project Summary/Abstract Caloric restriction (CR) retards aging in many species. Obesity increases mortality rate in humans. Yet beyond this superficial commonality, the connections between these two phenomena are incompletely known. So to, the mechanisms behind obesity's deleterious and CR's salubrious effects are minimally known and almost certainly manifold. Formerly, a common view was that CR's anti-aging effects were not related to reduced body weight or body fat. Today there is rekindled interest in the role of adiposity and energetics in longevity. New data from model organisms and clinical, laboratory, and epidemiologic studies in humans all suggest that adiposity may indeed play a role in the life-prolonging effects of CR and in the life-shortening effects of obesity. Access to several emerging resources (NHANES BIA and DXA data, The Health ABC Study, the CALERIE studies, non-human primate and mouse models) offer the opportunity to address new questions about the extent to which reduced energy intake, negative energy balance, lower body weight, reduced body fat, reduced body fat in specific depots, the dynamic process of weight or fat loss, or even hunger per se play roles in influencing longevity. This meeting will assemble a diverse highly-interdisciplinary group of investigators to address the connections among body weight, adiposity, energetics and longevity. R13 Body Weight, Adiposity, Energetics and Longevity: Project Narrative There is complex interactions among body weight, adiposity, energetic, and longevity. This 2-day meeting will bring together expert scientists from diverse disciplines to explore unanswered questions about these interactions and to introduce novel thoughts for future research. [unreadable] [unreadable] [unreadable]