Editing Appetite

{{Short description|Desire to eat food}}
{{other uses}}
{{distinguish|apatite|hunger}}
[[File:Piece of chocolate cake on a white plate decorated with chocolate sauce.jpg|thumb|Appealing food may provoke appetite even in the absence of hunger.]]
'''Appetite''' is the desire to eat food items, usually due to [[Hunger (physiology)|hunger]]. Appealing foods can stimulate appetite even when hunger is absent, although appetite can be greatly reduced by [[Hunger (motivational state)|satiety]].<ref name="pmid21340584">{{cite journal | vauthors = Egecioglu E, Skibicka KP, Hansson C, Alvarez-Crespo M, Friberg PA, Jerlhag E, Engel JA, Dickson SL | display-authors = 6 | title = Hedonic and incentive signals for body weight control | journal = Reviews in Endocrine & Metabolic Disorders | volume = 12 | issue = 3 | pages = 141–51 | date = September 2011 | pmid = 21340584 | pmc = 3145094 | doi = 10.1007/s11154-011-9166-4 }}</ref> Appetite exists in all higher life-forms, and serves to regulate adequate energy intake to maintain [[metabolism|metabolic]] needs. It is regulated by a close interplay between the [[digestive tract]], [[adipose tissue]] and the [[brain]]. Appetite has a relationship with every individual's behavior. [[Appetitive behaviour]] also known as [[approach 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 (symptom)|anorexia]], while [[polyphagia]] (or "hyperphagia") is increased eating. Dysregulation of appetite contributes to [[ARFID]], [[anorexia nervosa]], [[bulimia nervosa]], [[cachexia]], [[overeating]], and [[binge eating disorder]].

==Role in disease==
A limited or excessive appetite is not necessarily pathological. Abnormal appetite could be defined as eating habits causing [[malnutrition]] and related conditions such as [[obesity]] and its related problems.

Both genetic and environmental factors may regulate appetite, and abnormalities in either may lead to abnormal appetite. Poor appetite ([[anorexia (symptom)|anorexia]]) can have a number of causes, but may be a result of physical (infectious, autoimmune or malignant disease) or psychological (stress, mental disorders) factors. Likewise, [[hyperphagia]] (excessive eating) may be a result of hormonal imbalances, mental disorders (e.g., [[clinical depression|depression]]) and others. [[Dyspepsia]], also known as indigestion, can also affect appetite as one of its symptoms is feeling "overly full" soon after beginning a meal.<ref>{{cite web |publisher=National Digestive Diseases Information Clearinghouse (NDDIC) |url=http://digestive.niddk.nih.gov/ddiseases/pubs/indigestion/ |title=Indigestion |website=Digestive.niddk.nih.gov |access-date=2011-12-04 |archive-url=https://web.archive.org/web/20141105001458/http://digestive.niddk.nih.gov/ddiseases/pubs/indigestion/ |archive-date=2014-11-05 |url-status=dead }}</ref> [[Taste]] and [[Olfaction|smell]] ("[[dysgeusia]]", bad taste) or the lack thereof may also affect appetite.<ref>{{cite journal | vauthors = Henkin RI, Levy LM, Fordyce A | title = Taste and smell function in chronic disease: a review of clinical and biochemical evaluations of taste and smell dysfunction in over 5000 patients at The Taste and Smell Clinic in Washington, DC | journal = American Journal of Otolaryngology | volume = 34 | issue = 5 | pages = 477–89 | date = 2013-09-01 | pmid = 23731850 | doi = 10.1016/j.amjoto.2013.04.006 }}</ref>

Abnormal appetite may also be linked to genetics on a chromosomal scale, shown by the 1950s discovery of [[Prader–Willi syndrome]], a type of obesity caused by chromosome alterations. Additionally, anorexia nervosa and bulimia nervosa are more commonly found in females than males&nbsp;– thus hinting at a possibility of a linkage to the X-chromosome.<ref name="pmid16837373">{{cite journal | vauthors = Owen JB | title = Weight control and appetite--a genetic perspective | journal = Clinical Nutrition | volume = 9 | issue = 5 | pages = 291–3 | date = October 1990 | pmid = 16837373 | doi = 10.1016/0261-5614(90)90039-U }}</ref>

=== Eating disorders ===
Dysregulation of appetite lies at the root of [[anorexia nervosa]], [[bulimia nervosa]], and [[binge eating disorder]]. Anorexia nervosa is a mental disorder characterized as severe dietary restriction and intense fear of weight gain. Furthermore, persons with anorexia nervosa may exercise ritualistically. Individuals who have anorexia have high levels of [[ghrelin]], a hormone that stimulates appetite, so the body is trying to cause hunger, but the urge to eat is being suppressed by the person.<ref>{{cite book | vauthors = Schacter DT, Gilbert DT, Wegner DM |year=2011 |title=Psychology |url=https://archive.org/details/psychology0000scha |url-access=registration |edition=2nd |place=New York, NY |publisher=Worth Publishers|isbn=9781429237192 }}</ref> Binge eating disorder (commonly referred to as BED) is described as eating excessively (or uncontrollably) between periodic time intervals. The risk for BED can be present in children and most commonly manifests during adulthood. Studies suggest that the heritability of BED in adults is approximately 50%.<ref>{{cite journal | vauthors = Tanofsky-Kraff M, Bulik CM, Marcus MD, Striegel RH, Wilfley DE, Wonderlich SA, Hudson JI | title = Binge eating disorder: the next generation of research | journal = The International Journal of Eating Disorders | volume = 46 | issue = 3 | pages = 193–207 | date = April 2013 | pmid = 23354950 | pmc = 3600071 | doi = 10.1002/eat.22089 }}</ref> Similarly to bulimia, some people may be involved in purging and binging. They might vomit after food intake or take purgatives. [[Body dysmorphic disorder]] may involve food restriction in an attempt to deal with a perceived fault, and may be associated with depression and social isolation.<ref>{{cite journal | vauthors = Phillips KA | title = Body dysmorphic disorder: the distress of imagined ugliness | journal = The American Journal of Psychiatry | volume = 148 | issue = 9 | pages = 1138–49 | date = September 1991 | pmid = 1882990 | doi = 10.1176/ajp.148.9.1138 }}</ref>

=== Obesity ===
Various hereditary forms of obesity have been traced to defects in hypothalamic signaling (such as the leptin receptor and the [[melanocyte-stimulating hormone|MC-4]] receptor) or are still awaiting characterization&nbsp;– [[Prader-Willi syndrome]]&nbsp;– in addition, decreased response to [[satiety]] may promote development of [[obesity]].<ref>{{cite journal | vauthors = Lawton CL |title=Obesity: a disorder of appetite |journal=Practical Diabetes International |year=1993 |volume=10 |issue=1 |pages=10–12 |doi=10.1002/pdi.1960100105}}</ref> It has been found that ghrelin-reactive [[Immunoglobulin G|IgG]] immunoglobulins affect ghrelin's [[orexigenic]] response.<ref>{{cite journal | vauthors = Takagi K, Legrand R, Asakawa A, Amitani H, François M, Tennoune N, Coëffier M, Claeyssens S, do Rego JC, Déchelotte P, Inui A, Fetissov SO | display-authors = 6 | title = Anti-ghrelin immunoglobulins modulate ghrelin stability and its orexigenic effect in obese mice and humans | journal = Nature Communications | volume = 4 | pages = 2685 | date = 2013-10-25 | pmid = 24158035 | pmc = 3826639 | doi = 10.1038/ncomms3685 | bibcode = 2013NatCo...4.2685T }}</ref>

Other than genetically stimulated appetite abnormalities, there are physiological ones that do not require genes for activation. For example, [[ghrelin]] and [[leptin]] are released from the stomach and [[Adipocyte|adipose cells]], respectively, into the blood stream. Ghrelin stimulates feelings of hunger, whereas leptin stimulates feelings of satisfaction from food.<ref>{{cite web |url=http://www.montereydiet.com/ghrelin_and_leptin.html |title=How The Hormones Ghrelin and Leptin Affect Appetite |publisher=The Monterey Diet |date=<!--not specified--> |access-date=2013-03-09 |archive-date=2020-05-13 |archive-url=https://web.archive.org/web/20200513062423/http://www.montereydiet.com/ghrelin_and_leptin.html |url-status=usurped }}</ref> Any changes in normal production levels of these two hormones can lead to obesity. The amount of leptin hormone production is stimulated by body fat percentage. When body fat accumulates there is overproduction of leptin causing a resistant hypothalamus and eventually almost no leptin effect. From then all ghrelin production causes insatiable appetite.<ref>{{cite journal | vauthors = Sader S, Nian M, Liu P | title = Leptin: a novel link between obesity, diabetes, cardiovascular risk, and ventricular hypertrophy | journal = Circulation | volume = 108 | issue = 6 | pages = 644–6 | date = August 2003 | pmid = 12912793 | doi = 10.1161/01.CIR.0000081427.01306.7D | doi-access = free }} {{open access}}</ref>

=== Pediatric eating problems ===
Eating issues such as "[[Avoidant/restrictive food intake disorder|picky eating]]" affects about 25% of children, but among children with [[Developmental disorder|development disorders]] this number may be significantly higher, which in some cases may be related to the sounds, smells, and tastes ([[sensory processing disorder]]).<ref>{{cite journal | vauthors = Nadon G, Feldman DE, Dunn W, Gisel E | title = Association of sensory processing and eating problems in children with autism spectrum disorders | journal = Autism Research and Treatment | volume = 2011 | pages = 541926 | date = 2011-09-22 | pmid = 22937249 | pmc = 3420765 | doi = 10.1155/2011/541926 | doi-access = free }}</ref>

==Pharmacology and treatment==
The [[glycemic index]] is thought to affect [[Hunger (motivational state)|satiety]]; a study investigating the effect of satiety found that a high-glycemic food, potatoes, reduced appetite more than a low glycemic index food.<ref>{{cite journal | vauthors = Kaplan RJ, Greenwood CE | title = Influence of dietary carbohydrates and glycaemic response on subjective appetite and food intake in healthy elderly persons | journal = International Journal of Food Sciences and Nutrition | volume = 53 | issue = 4 | pages = 305–16 | date = July 2002 | pmid = 12090026 | doi = 10.1080/09637480220138160 | s2cid = 24129879 }}</ref>

=== Suppression ===
Mechanisms controlling appetite are a potential target for weight loss drugs. Appetite control mechanisms seem to strongly counteract undereating, whereas they appear weak to control overeating. Early [[anorectic]]s (appetite suppressants) were [[fenfluramine]] and [[phentermine]]. A more recent addition is [[sibutramine]] which increases [[serotonin]] and [[noradrenaline]] levels in the [[central nervous system]], but had to be withdrawn from the market when it was shown to have an adverse cardiovascular risk profile. Similarly, the appetite suppressant [[rimonabant]] (a cannabinoid receptor antagonist) had to be withdrawn when it was linked with worsening depression and increased risk of suicide. Recent reports on [[Recombinant DNA|recombinant]] [[PYY 3-36]] suggest that this agent may contribute to [[weight loss]] by suppressing appetite.

Given the epidemic proportions of [[obesity]] in the Western world and the fact that it is increasing rapidly in some poorer countries, observers{{Who|date=August 2010}} expect developments in this area to snowball in the near future.

=== Stimulation ===
Weight loss or loss of appetite ("[[cachexia]]") is an effect of some diseases, and a side effect of some [[prescription drug]]s. Stimulants such as [[methylphenidate]] commonly reduce appetite in patients,<ref>{{Cite web|date=2011-07-20|title=Ritalin LA Prescribing Information|url=http://www.pharma.us.novartis.com/product/pi/pdf/ritalin_la.pdf|url-status=live|archive-url=https://web.archive.org/web/20110720004745/http://www.pharma.us.novartis.com/product/pi/pdf/ritalin_la.pdf|archive-date=2011-07-20|access-date=2020-06-04|publisher=Novartis}}</ref> and have been prescribed off-label for weight loss.<ref>{{Cite web|title=How ADHD Medication Can Affect Your Weight|url=https://www.webmd.com/add-adhd/medication-weight|access-date=2020-06-04|website=WebMD|language=en}}</ref>  Three agents are approved for appetite stimulation in the United States: [[megestrol acetate]] - a [[progesterone]] available as an oral tablet, [[oxandrolone]] - an oral [[anabolic steroid]], and [[dronabinol]] - [[Tetrahydrocannabinol|THC]], the principal [[cannabinoid]] in [[marijuana]], available in an oral capsule.<ref>{{cite web| vauthors = Archer M, Steinvoort C, Larson B, Oderda G |title=Agents used as appetite stimulants: Drug class review|url=http://www.health.utah.gov/pharmacy/ptcommittee/files/Criteria%20Review%20Documents/03.14/Appetite%20Stimulant%20Drug%20Class%20Review.pdf#page=3|publisher=University of Utah College of Pharmacy|date=2014|access-date=19 April 2019|archive-url=https://web.archive.org/web/20161009021247/http://www.health.utah.gov/pharmacy/ptcommittee/files/Criteria%20Review%20Documents/03.14/Appetite%20Stimulant%20Drug%20Class%20Review.pdf#page=3|archive-date=9 October 2016|url-status=dead}}</ref>

[[Ghrelin]], a gut hormone recognized as affecting appetite, is under investigation.<ref name="Khatib" /> Ghrelin itself must be delivered [[Intravenous therapy|parenterally]]<ref name="Khatib" />{{Rp|2178}} and research has therefore focused on substances that can be taken orally. Rikkunshito, a traditional Japanese [[Kampo|Kampo medicine]], is under preliminary research for its potential to stimulate ghrelin and appetite.<ref name="Khatib">{{cite journal | vauthors = Khatib MN, Gaidhane A, Gaidhane S, Quazi ZS | title = Ghrelin as a Promising Therapeutic Option for Cancer Cachexia | journal = Cellular Physiology and Biochemistry | volume = 48 | issue = 5 | pages = 2172–2188 | year = 2018 | pmid = 30110683 | doi = 10.1159/000492559 | doi-access = free }}</ref>

== See also ==
{{wikiquote}}
{{wiktionary|appetite}}
* [[Satiety value]]
* [[Specific appetite]]
* [[Orexigenic]]
* [[Adipsia]]

== References ==
{{reflist}}

{{Psychophysiology}}

{{Authority control}}

[[Category:Endocrinology]]
[[Category:Eating behaviors]]