Appetite
Desire to eat, regulating energy intake across higher life-forms.
Appetite refers to the desire to eat, typically driven by hunger. Even when hunger is absent, appealing foods can trigger appetite, though feeling full can greatly reduce it. All higher life-forms experience appetite, which helps ensure they take in enough energy to meet their metabolic needs. This drive is regulated through a complex interaction among the digestive tract, fat tissue, and the brain, and it is closely tied to each person's behavior. Behaviors involving energy intake include appetitive (or approach) behavior, consummatory behavior, as well as processes like digestion, absorption, and thermogenesis, while other behaviors affect energy release. Stress can raise appetite levels, leading to increased food intake. A reduced desire to eat is called anorexia, while increased eating is known as polyphagia or hyperphagia. Problems with appetite regulation are linked to conditions such as ARFID, anorexia nervosa, bulimia nervosa, cachexia, overeating, and binge eating disorder.
A limited or excessive appetite is not always pathological. Abnormal appetite can be defined as eating habits that cause malnutrition and related conditions like obesity and its complications. Both genetic and environmental factors can influence appetite, and abnormalities in either may lead to appetite problems. Poor appetite (anorexia) can stem from physical causes such as infectious, autoimmune, or malignant disease, or from psychological factors like stress or mental disorders. Excessive eating (hyperphagia) may result from hormonal imbalances, mental disorders such as depression, and other causes. Dyspepsia, or indigestion, can affect appetite by causing a feeling of being overly full soon after starting a meal. Taste and smell issues—like dysgeusia (bad taste) or the absence of these senses—can also impact appetite. Abnormal appetite may have genetic links at the chromosomal level, as shown by the discovery of Prader–Willi syndrome in the 1950s, a type of obesity caused by chromosome alterations. Additionally, anorexia nervosa and bulimia nervosa occur more often in females than males, hinting at a possible connection to the X-chromosome.
Dysregulation of appetite is at the core of anorexia nervosa, bulimia nervosa, and binge eating disorder. Anorexia nervosa is a mental disorder marked by severe dietary restriction and an intense fear of weight gain, and those affected m
- field
- Physiology, Psychology, Medicine
- known_for
- Regulation of energy intake, link to eating disorders and obesity
- related_conditions
- Anorexia, polyphagia, ARFID, bulimia nervosa, cachexia, binge eating disorder
- key_hormones
- Ghrelin (stimulates hunger), Leptin (stimulates satisfaction)
- genetic_link
- Prader–Willi syndrome, possible X-chromosome linkage
Lore & Background
Appetite is regulated by a close interplay between the digestive tract, adipose tissue, and the brain. Appealing foods can stimulate appetite even when hunger is absent, although appetite can be greatly reduced by satiety. 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. Dysregulation of appetite contributes to ARFID, anorexia nervosa, bulimia nervosa, cachexia, overeating, and binge eating disorder.
Both genetic and environmental factors may regulate appetite, and abnormalities in either may lead to abnormal appetite. Early anorectics (appetite suppressants) included amphetamine (introduced in the 1930s) and other sympathomimetic amines, with fenfluramine and phentermine being later additions used in combination during the 1990s. Poor appetite (
Reader's Guide
Appetite is central to understanding both normal energy balance and a wide range of disorders. Its dysregulation lies at the root of anorexia nervosa, bulimia nervosa, and binge eating disorder. Anorexia nervosa involves severe dietary restriction and intense fear of weight gain, with individuals having high levels of ghrelin, a hormone that stimulates appetite, yet the urge to eat is suppressed. Binge eating disorder is described as eating excessively between periodic time intervals, with heritability in adults approximately 50%. Obesity can result from hereditary forms traced to defects in hypothalamic signaling or from physiological changes in ghrelin and leptin production. Appetite control mechanisms strongly counteract undereating but appear weak at controlling overeating. Pharmacological treatments have included appetite suppressants such as fenfluramine, phentermine, sibutramine, and rimonabant, though some were withdrawn due to adverse effects. Appetite stimulants include megestrol acetate, oxandrolone, and dronabinol. The glycemic index is thought to affect satiety, but a study found it did not predict effects on satiety and food intake. Given the epidemic proportions of obesity in the Western world and its rapid increase in some poorer countries, developments in appetite research are expected to snowball.
Did You Know?
- Appetite exists in all higher life-forms and serves to regulate adequate energy intake to maintain metabolic needs.
- Ghrelin-reactive IgG immunoglobulins affect ghrelin's orexigenic response.
- Eating issues such as 'picky eating' affect about 25% of children, but among children with development disorders this number may be significantly higher.
- Early anorectics (appetite suppressants) were fenfluramine and phentermine.
More in General Health And Wellness 1-24
Spotted an error? Know more?
This is a living reference — every entry is fact-audited, and reader corrections feed straight into our audit queue. Suggest an edit · See this site's audit record