The negative feedback model for the regulation of body weight. In this model, peripheral signals from energy stores (adipose tissue, muscle, and liver) as well as hormonal and gastrointestinal signals act on the central controllers in the brain, indicating the state of the external and internal environment as they relate to food, metabolic rate, and activity behaviors. In turn, the central controllers integrate these signals and transduce these messages into efferent signals governing the behavioral search for the acquisition of food, as well as modulating its subsequent deposition into energy storage compartments, such as adipose tissue, liver, and muscle. Afferent signals, efferent signals, and central controllers can all be influenced by an organism’s genetic makeup, hence the inter-individual variability in weight change in response to a perturbed energy balance.