Neurophysiology of hunger and satiety.

Hunger is defined as a strong desire or need for food while satiety is the condition of being full or gratified. The maintenance of energy homeostasis requires a balance between energy intake and energy expenditure. The regulation of food intake is a complex behavior. It requires discrete nuclei within the central nervous system (CNS) to detect signals from the periphery regarding metabolic status, process and integrate this information in a coordinated manner and to provide appropriate responses to ensure that the individual does not enter a state of positive or negative energy balance. This review of hunger and satiety will examine the CNS circuitries involved in the control of energy homeostasis as well as signals from the periphery, both hormonal and neural, that convey pertinent information regarding short-term and long-term energy status of the individual. (c) 2008 Wiley-Liss, Inc.