Appetite
Desire to eat, regulating energy intake across higher life-forms.
Appetite is the desire to eat food items, usually due to hunger. It exists in all higher life-forms and serves to regulate adequate energy intake to maintain metabolic needs. Appetite is regulated by a close interplay between the digestive tract, adipose tissue, and the brain, and has a relationship with every individual's behavior.
- field
- Physiology, Psychology, Medicine
- known_for
- Regulation of energy intake, role in eating disorders and obesity
- related_disorders
- Anorexia nervosa, bulimia nervosa, binge eating disorder, cachexia, ARFID
- key_hormones
- Ghrelin (stimulates hunger), Leptin (stimulates satisfaction)
- genetic_link
- Prader–Willi syndrome (chromosome alterations)
Lore & Background
Appetite is the desire to eat food items, usually due to hunger. Appealing foods can stimulate appetite even when hunger is absent, although appetite can be greatly reduced by satiety. It is regulated by a close interplay between the digestive tract, adipose tissue, and the brain. Appetitive behaviour and consummatory behaviour are the only processes that involve energy intake, whereas all other behaviours affect the release of energy. When stressed, appetite levels may increase and result in an increase of food intake. Decreased desire to eat is termed anorexia, while polyphagia (or 'hyperphagia') is increased eating.
Reader's Guide
Dysregulation of appetite contributes to anorexia nervosa, bulimia nervosa, binge eating disorder, cachexia, overeating, and ARFID. Both genetic and environmental factors may regulate appetite, and abnormalities in either may lead to abnormal appetite. Poor appetite (anorexia) can result from physical or psychological factors, while hyperphagia may result from hormonal imbalances or mental disorders. Various hereditary forms of obesity have been traced to defects in hypothalamic signaling, such as the leptin receptor and the MC-4 receptor. Ghrelin and leptin are released from the stomach and adipose cells, respectively; ghrelin stimulates feelings of hunger, whereas leptin stimulates feelings of satisfaction. Changes in normal production levels of these hormones can lead to obesity. Appetite control mechanisms are a potential target for weight loss drugs, though some appetite suppressants have been withdrawn due to adverse effects. Stimulants such as methylphenidate commonly reduce appetite, while agents like megestrol acetate, oxandrolone, and dronabinol are approved for appetite stimulation in the United States.
Did You Know?
- Appetite exists in all higher life-forms.
- Ghrelin-reactive IgG immunoglobulins affect ghrelin's orexigenic response.
- Prader–Willi syndrome is a type of obesity caused by chromosome alterations.
- The glycemic index of foods did not predict effects on satiety and food intake in one study.
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