Intake[edit]

Energy intake is measured by the amount of calories consumed from food and fluids.^[1] Energy intake is modulated by hunger, which is primarily regulated by the hypothalamus,^[1] and choice, which is determined by the sets of brain structures that are responsible for stimulus control (i.e., operant conditioning and classical conditioning) and cognitive control of eating behavior.^[8][9] Hunger is regulated in part by the action of certain peptide hormones and neuropeptides (e.g., insulin, leptin, ghrelin, and neuropeptide Y, among others) in the hypothalamus.^[1][10]