Control of food intake in the obese

Food intake (eating) is a form of behavior that is subject to conscious con trol. In practice, many obese and weight-gaining individuals claim that the ir eating is out of (their) control. Mechanistic models describe the interp lay of biological and environmental forces that control food intake. Howeve r, because human food intake is characterized by individuals intervening to adjust their own patterns of behavior, food intake should reflect interact ions among biology, environment, and attempted self-imposed control of beha vior. In general, humans display a system of weight regulation that is asym metrical-a reduction in body weight is strongly defended but weight gain is not. The body seems to tolerate a positive energy balance. There is no mec hanism that can detect a positive energy balance per se or that can impleme nt a sufficiently strong correction to behavior to maintain body weight in an environment that promotes consumption. The evolutionary process has favo red biological traits associated with preferences for high energy density ( sweet and/or fatty) energy-yielding foods. The control of food intake in ob ese or weight-gaining individuals may display various risk factors that fav or an increase in energy. These include the preference for high energy-dens e over low energy-dense foods, weal, postprandial inhibitory signaling, str ong hunger traits associated with low leptin levels after weight loss, and the consumption of fatty foods. In addition, many individuals (up to 47% of some samples) display binge eating patterns, whereas similar to 16% show e ither night eating or nocturnal eating. Because energy expenditure is only loosely coupled to energy intake, sedentariness does not down-regulate food intake.