ABSTRACT
Eating is also controlled by external factors, both sensory and psychological. The administration of opioid antagonists reduces pleasantness ratings of foods, suggesting that the rewarding properties of eating are due to the release of endogenous opioids in the hypothalamus. During the consumption of a particular food, the rate of eating slows, and this is followed for up to an hour by a decrease in palatability. The eating of less palatable foods more often has a negative association (threats or punishment), while inherently palatable foods, high in carbohydrates often combined with fats, are presented in pleasant contexts (parties, treats, etc.). The preference for energy-dense foods may be based on endogenous opioid circuits. A genetic predisposition to obesity in humans interacts with exposure to particular family, social, and cultural environments. Disorders such as bulimia and anorexia nervosa are best not considered primarily as disorders of eating or weight control.
