Food and Fluid Intake

Abstract

The ingestive behaviors of eating and drinking play primary roles in the maintenance of fluid homeostasis and energy balance. Eating and drinking occur intermittently, they both renew and anticipate depletions, and their controls are complex and redundant. The physiological controls of food intake can be divided into systems that mediate: (1) signals related to metabolic state, especially the degree of adiposity stores, (2) affective signals related to taste and nutritional consequences that serve to reinforce aspects of ingestive behavior, and (3) signals that arise within an individual meal that produce satiety. Interactions among these systems permit the appropriate patterning of feeding that lead to the overall regulation of energy balance. The controls of fluid balance depend on interactions among three relatively well characterized systems related to: (1) neural and hormonal signals arising from the detection of plasma osmolality and extracellular fluid volume, which influence the initiation of bouts of fluid ingestion; (2) neural and hormonal signals related to myriad factors that lead to satiety and thus terminate bouts of drinking; and (3) brain sites that receive and integrate these signals and which elicit appropriate physiological and behavioral responses.