Experimental Approach to Test Predictions of Body Weight Regulation Models

The regulation of human body weight and fatness is not fully understood. Although some models of regulation have been proposed (set point, dual-intervention point, others), no studies have been designed to test their predictions. In this pilot and feasibility study, the investigators will implement an experimental approach to test the predictions of models of body weight regulation in humans. Men and women with either low body weight or obesity will be exposed to a 2-day fasting followed by a 2-day ad-libitum refeeding. During the entire fasting-refeeding period, energy intake and expenditure will be accurately measured within metabolic chambers. The investigators will therefore determine the compensatory responses to fasting elicited to prevent weight loss. The results will serve to design and power future studies to better understand body weight regulation.