Anorexia nervosa is an eating disorder characterized by attempts to lose weight, to the point of starvation. A person with anorexia nervosa may exhibit a number of signs and symptoms, the type and severity of which may vary and may be present but not readily apparent.

Anorexia nervosa, and the associated malnutrition that results from self-imposed starvation, can cause complications in every major organ system in the body. Hypokalaemia, a drop in the level of potassium in the blood, is a sign of anorexia nervosa. A significant drop in potassium can cause abnormal heart rhythms, constipation, fatigue, muscle damage and paralysis.

Symptoms may include:

- A low body mass index for one's age and height.

- Amenorrhea, a symptom that occurs after prolonged weight loss; causes menses to stop, hair becomes brittle, and skin becomes yellow and unhealthy.

- Fear of even the slightest weight gain; taking all precautionary measures to avoid weight gain or becoming "overweight".

- Rapid, continuous weight loss.

- Lanugo: soft, fine hair growing over the face and body.

- An obsession with counting calories and monitoring fat contents of food.

- Preoccupation with food, recipes, or cooking; may cook elaborate dinners for others, but not eat the food themselves or consume a very small portion.

- Food restrictions despite being underweight or at a healthy weight.

- Food rituals, such as cutting food into tiny pieces, refusing to eat around others and hiding or discarding of food.

- Purging: May use laxatives, diet pills, ipecac syrup, or water pills to flush food out of their system after eating or may engage in self-induced vomiting though this is a more common symptom of bulimia.

- Excessive exercise including micro-exercising, for example making small persistent movements of fingers or toes.

- Perception of self as overweight, in contradiction to an underweight reality.

- Intolerance to cold and frequent complaints of being cold; body temperature may lower (hypothermia) in an effort to conserve energy due to malnutrition.

- Hypotension or orthostatic hypotension.

- Bradycardia or tachycardia.

- Depression, anxiety disorders and insomnia.

- Solitude: may avoid friends and family and become more withdrawn and secretive.

- Abdominal distension.

- Halitosis (from vomiting or starvation-induced ketosis).

- Dry hair and skin, as well as hair thinning.

- Chronic fatigue.

- Rapid mood swings.

- Having feet discoloration causing an orange appearance.

- Having severe muscle tension + aches and pains.

- Evidence/habits of self harming or self-loathing.

- Admiration of thinner people.

Interoception has an important role in homeostasis and regulation of emotions and motivation. Anorexia has been associated with disturbances to interoception. People with anorexia concentrate on distorted perceptions of their body exterior due to fear of looking overweight. Aside from outer appearance, they also report abnormal bodily functions such as indistinct feelings of fullness. This provides an example of miscommunication between body and brain. Further, people with anorexia experience abnormally intense cardiorespiratory sensations, particularly of the breath, most prevalent before they consume a meal. People with anorexia also report inability to distinguish emotions from bodily sensations in general, called alexithymia. In addition to metacognition, people with anorexia also have difficultly with social cognition including interpreting other’s emotions, and demonstrating empathy. Abnormal interoceptive awareness like these examples have been observed so frequently in anorexia that they have become key characteristics of the illness.

Bulimia typically involves rapid and out-of-control eating, which may stop when the bulimic is interrupted by another person or the stomach hurts from over-extension, followed by self-induced vomiting or other forms of purging. This cycle may be repeated several times a week or, in more serious cases, several times a day and may directly cause:

- Chronic gastric reflux after eating, secondary to vomiting

- Dehydration and hypokalemia due to renal potassium loss in the presence of alkalosis and frequent vomiting

- Electrolyte imbalance, which can lead to abnormal heart rhythms, cardiac arrest, and even death

- Esophagitis, or inflammation of the esophagus

- Mallory-Weiss tears

- Boerhaave syndrome, a rupture in the esophageal wall due to vomiting

- Oral trauma, in which repetitive insertion of fingers or other objects causes lacerations to the lining of the mouth or throat

- Russell's sign: calluses on knuckles and back of hands due to repeated trauma from incisors

- Perimolysis, or severe dental erosion of tooth enamel

- Swollen salivary glands (for example, in the neck, under the jaw line)

- Gastroparesis or delayed emptying

- Constipation

- Peptic ulcers

- Infertility

- Constant weight fluctuations are common

These are some of the many signs that may indicate whether someone has bulimia nervosa:

- A fixation on the number of calories consumed

- A fixation on and extreme consciousness of ones weight

- Low self-esteem and/or self harming

- Suicidal tendencies

- Low blood pressure

- An irregular menstrual cycle in woman

- Regular trips to the bathroom, especially soon after eating

- Depression, anxiety disorders and sleep disorders

- Frequent occurrences involving consumption of abnormally large portions of food

- The use of laxatives and diet pills

- Unhealthy/dry skin, hair, nails and lips

- A lack of energy

As with many psychiatric illnesses, delusions can occur, in conjunction with other signs and symptoms, leaving the person with a false belief that is not ordinarily accepted by others.

People with bulimia nervosa may also exercise to a point that excludes other activities.

With regards to interoception, people with bulimia report reduced sensitivity to many kinds of internal and external sensations. For example, some show increased thresholds to heat pain compared and report the same level of satiety after consuming more calories than do healthy subjects.

Bulimia nervosa is a disorder characterized by binge eating and purging, as well as excessive evaluation of one's self-worth in terms of body weight or shape. Purging can include self-induced vomiting, over-exercising, and the use of diuretics, enemas, and laxatives. Anorexia nervosa is characterized by extreme food restriction and excessive weight loss, accompanied by the fear of being fat. The extreme weight loss often causes women and girls who have begun menstruating to stop having menstrual periods, a condition known as amenorrhea. Although amenorrhea was once a required criterion for the disorder, it is no longer required to meet criteria for anorexia nervosa due to its exclusive nature for sufferers who are male, post-menopause, or who do not menstruate for other reasons. The DSM-5 specifies two subtypes of anorexia nervosa—the restricting type and the binge/purge type. Those who suffer from the restricting type of anorexia nervosa restrict food intake and do not engage in binge eating, whereas those suffering from the binge/purge type lose control over their eating at least occasionally and may compensate for these binge episodes. The most notable difference between anorexia nervosa binge/purge type and bulimia nervosa is the body weight of the person. Those diagnosed with anorexia nervosa binge/purge type are underweight, while those with bulimia nervosa may have a body weight that falls within the range from normal to obese.

These eating disorders are specified as mental disorders in standard medical manuals, such as in the ICD-10, the DSM-5, or both.

- Anorexia nervosa (AN), characterized by lack of maintenance of a healthy body weight, an obsessive fear of gaining weight or refusal to do so, and an unrealistic perception, or non-recognition of the seriousness, of current low body weight. Anorexia can cause menstruation to stop, and often leads to bone loss, loss of skin integrity, etc. It greatly stresses the heart, increasing the risk of heart attacks and related heart problems. The risk of death is greatly increased in individuals with this disease. The most underlining factor researchers are starting to take notice of is that it may not just be a vanity, social, or media issue, but it could also be related to biological and or genetic components. The DSM-5 contains many changes that better represent patients with these conditions. The DSM-IV required amenorrhea (the absence of the menstrual cycle) to be present in order to diagnose a patient with anorexia. This is no longer a requirement in the DSM-5.

- Bulimia nervosa (BN), characterized by recurrent binge eating followed by compensatory behaviors such as purging (self-induced vomiting, eating to the point of vomiting, excessive use of laxatives/diuretics, or excessive exercise). Fasting and over-exercising may also be used as a method of purging following a binge.

- Muscle dysmorphia is characterized by appearance preoccupation that one's own body is too small, too skinny, insufficiently muscular, or insufficiently lean. Muscle dysmorphia affects mostly males.

- Binge Eating Disorder (BED), characterized by recurring binge eating at least once a week for over a period of 3 months while experiencing lack of control and guilt after overeating. The disorder can develop within individuals of a wide range of ages and socioeconomic classes.

- Other Specified Feeding or Eating Disorder (OSFED) is an eating or feeding disorder that does not meet full DSM-5 criteria for AN, BN, or BED. Examples of otherwise-specified eating disorders include individuals with atypical anorexia nervosa, who meet all criteria for AN except being underweight, despite substantial weight loss; atypical bulimia nervosa, who meet all criteria for BN except that bulimic behaviors are less frequent or have not been ongoing for long enough; purging disorder; and night eating syndrome.

Exercise Bulimia can sometimes go unnoticed because exercise is something that is seen as healthy, but just because a person looks healthy does not mean they are. Compulsive exercisers will often schedule their lives around exercise just as those with eating disorders schedule their lives around eating (or not eating). Other indications of compulsive exercise are:

- Missing work, school and other important events in order to work out

- Working out with an injury or while sick

- Working out secretly or away from noticeable sight

- Becoming unusually depressed if unable to exercise

- Working out for hours at a time each day

- Not taking any rest or recovery days

- Defining self-worth in terms of performance

- Justifies excessive behavior by defining self as a "special" elite athlete

- Depression or agitation when unable to work out

- Amenorrhea, the stop of a woman's menstrual cycle

- Isolation from others while working out

- Lack of interest in friends and eating

- Lack of sleep

Binge eating is the core symptom of BED; however, not everyone who binge eats has BED. An individual may occasionally binge eat without experiencing many of the negative physical, psychological, or social effects of BED. This example may be considered an eating problem (or not), rather than a disorder. Precisely defining binge eating can be problematic, however binge eating episodes in BED are generally described as having the following potential features:

- Eating much faster than normal during a binge perhaps in a short space of time

- Eating until feeling uncomfortably full

- Eating a large amount when not hungry

- Subjective loss of control over how much or what is eaten

- Binges may be planned in advance, involving the purchase of special binge foods, and the allocation of specific time for binging, sometimes at night

- Eating alone or secretly due to embarrassment over the amount of food consumed

- There may be a dazed mental state during the binge

- Not being able to remember what was eaten after the binge

- Feelings of guilt, shame or disgust following a food binge

In contrast to bulimia nervosa, binge eating episodes are not regularly followed by activities intended to prevent weight gain, such as self-induced vomiting, laxative or enema misuse, or strenuous exercise. BED is characterized more by overeating than dietary restriction and over concern about body shape. Obesity is common in persons with BED, as are depressive features, low self-esteem, stress and boredom.

The three general categories for an EDNOS diagnosis are subthreshold symptoms of anorexia or bulimia, a mixture of both anorexia or bulimia, and eating behaviors that are not particularized by anorexia and bulimia. EDNOS is no longer considered a diagnosis in "DSM-5"; those displaying symptoms of what would previously have been considered EDNOS are now classified under Other Specified Feeding or Eating Disorder.

Someone with anorexia athletica can experience numerous signs and symptoms, a few of which are listed below. The seriousness of the symptoms is dependent on the individual, and more symptoms come with the length the athlete excessively exercises. If anorexia athletica persists for long enough, the individual can become malnourished, which eventually leads to further complications in major organs such as the liver, kidney, heart and brain.

- Excessive exercise

- Obsessive behavior with calories, fat, and weight

- Self-worth is based on physical performance

- Enjoyment of sports is diminished or gone

- Denying the over exercising is a problem

Rather than providing specific diagnostic criteria for EDNOS, the fourth revision of the "Diagnostic and Statistical Manual of Mental Disorders" ("DSM-IV") listed six non-exhaustive example presentations, including individuals who:

1. Meet all criteria for anorexia nervosa except their weight falls within the normal range

2. Meet all criteria for bulimia nervosa except they engage in binge eating or purging behaviors less than twice per week or for fewer than three months

3. Purge after eating small amounts of food while retaining a normal body weight

4. Repeatedly chew and spit out large amounts of food without swallowing

5. Do not meet criteria for binge eating disorder

Despite its subclinical status in "DSM-IV", available data suggest that EDNOS is no less severe than the officially recognized "DSM-IV" eating disorders. In a comprehensive meta-analysis of 125 studies, individuals with EDNOS exhibited similar levels of eating pathology and general psychopathology to those with anorexia nervosa and binge eating disorder, and similar levels of physical health problems as those with anorexia nervosa. Although individuals with bulimia nervosa scored significantly higher than those with EDNOS on measures of eating pathology and general psychopathology, those with EDNOS exhibited more physical health problems than those with bulimia nervosa.

Binge eating disorder (BED) is an eating disorder characterized by frequent and recurrent binge eating episodes with associated negative psychological and social problems, but without subsequent purging episodes (e.g. vomiting).

BED is a recently described condition, which was required to distinguish binge eating similar to that seen bulimia nervosa but without characteristic purging. Individuals who are diagnosed with bulimia nervosa and binge eating disorder exhibit similar patterns of compulsive overeating, neurobiological features of dysfunctional cognitive control and food addiction, and biological and environmental risk factors. Indeed, some consider BED a milder version of bulimia nervosa, and that the conditions are on the same spectrum.

Binge eating is one of the most prevalent eating disorders among adults, though there tends to be less media coverage and research about the disorder in comparison to anorexia nervosa and bulimia nervosa.

These are the short term symptoms of patients with diabulimia

- Constant urination

- Constant thirst

- Excessive appetite

- High blood glucose levels (often over 600 mg/dL or 33 mmol/L)

- Weakness

- Fatigue

- Large amounts of glucose in the urine

- Inability to concentrate

- Electrolyte disturbance

- Severe ketonuria, and, in DKA, severe ketonemia

- Low sodium levels

Purging disorder is an eating disorder characterized by recurrent purging (self-induced vomiting, misuse of laxatives, diuretics, or enemas) to control weight or shape in the absence of binge eating episodes.

Purging disorder differs from bulimia nervosa (BN) because individuals with purging disorder do not consume a large amount of food before they purge. In current diagnostic systems, purging disorder is a form of Other specified feeding or eating disorder (OSFED). Research indicates that purging disorder may be as common as bulimia nervosa or anorexia nervosa in women, that the syndrome is associated with clinically significant levels of distress, and that it appears to be distinct from bulimia nervosa on measures of hunger and ability to control food intake. Some of the signs of purging disorder are frequent trips to the bathroom directly after a meal, frequent use of laxatives, and obsession over one's appearance and weight. Other signs include swollen cheeks, popped blood vessels in the eyes, and clear teeth which are all signs of excessive vomiting.

These are the medium term symptoms of patients with diabulimia. They are prevalent when diabulimia has not been treated and hence also include the short term symptoms

- Muscle atrophy

- GERD

- Indigestion

- Severe weight loss

- Proteinuria

- Moderate to severe dehydration

- Edema with fluid replacement

- High cholesterol

The differential diagnoses of anorexia nervosa (AN) includes various types of medical and psychological conditions, which may be misdiagnosed as AN. In some cases, these conditions may be comorbid with AN because the misdiagnosis of AN is not uncommon. For example, a case of achalasia was misdiagnosed as AN and the patient spent two months confined to a psychiatric hospital. A reason for the differential diagnoses that surround AN arise mainly because, like other disorders, it is primarily, albeit defensively and adaptive for, the individual concerned.

Anorexia Nervosa is a psychological disorder characterized by extremely reduced intake of food. People suffering from Aneroxia Nervosa have a low self-image and consider themselves overweight.

Common behaviors and signs of someone suffering from AN:

- Forcing oneself to vigorously exercise even in adverse conditions or when their health does not permit it.

- Forcing own self to urinate and excrete waste product from the body.

- Using substituted amphetamines (stimulants that can reduce appetite) to reduce appetite.

- Skin turning yellow

Feeding disorder has been divided into six further sub-types:

1. Feeding disorder of state regulation

2. Feeding disorder of reciprocity (neglect)

3. Infantile anorexia

4. Sensory food aversion

5. Feeding disorder associated with concurrent medical condition

6. Post-traumatic feeding disorder

Anorexia athletica (sports anorexia), also referred to as hypergymnasia is an eating disorder characterized by excessive and compulsive exercise. An athlete suffering from sports anorexia tends to over exercise to give themselves a sense of having control over their body. Most often, people with the disorder tend to feel they have no control over their lives other than their control of food and exercise. In actuality, they have no control; they cannot stop exercising or regulating food intake without feeling guilty. Generally, once the activity is started, it is difficult to stop because the person is seen as being addicted to the method adopted.

Anorexia athletica is used to refer to "a disorder for athletes who engage in at least one unhealthy method of weight control". Unlike anorexia nervosa, anorexia athletica does not have as much to do with body image as it does with performance. Athletes usually begin by eating more 'healthy' foods, as well as increasing their training, but when people feel like that is not enough and start working out excessively and cutting back their caloric intake until it becomes a psychological disorder.

Hypergymnasia and anorexia athletica are not recognized as mental disorders in any of the medical manuals, such as the ICD-10 or the DSM-IV, nor is it part of the proposed revision of this manual, the DSM-5. If this were the case, there would be a 10–15% increase in mental disorders in sports. A study at the Anorexia Centre at Huddinge Hospital in Stockholm, Sweden showed that sports anorexia can result in mental disorders. The anxiety, stress, and pressure people with sports anorexia put on themselves (as well as the pressure parents and coaches can put on the athlete) can cause mental disorders.

Some of the differential or comorbid medical diagnoses may include:

- achalasia – There have been cases where achalasia, a disorder of the esophagus which affects peristalsis, has been misdiagnosed as AN. It has been reported in cases where there is sub-clinical manifestation of anorexia nervosa and also in cases where the full diagnostic criteria AN have been met.

- acute pandysautonomia is one form of an autonomic neuropathy, which is a collection of various syndromes and diseases which affect the autonomic neurons of the autonomic nervous system (ANS). Autonomic neuropathies may be the result of an inherited condition or they may be acquired due to various premorbid conditions such as diabetes and alcoholism, bacterial infection such as Lyme disease or a viral illness. Some of the symptoms of ANS which may be associated with an ED include nausea, dysphagia, constipation, pain in the salivary glands, early saiety. It also affects peristalsis in the stomach. Acute pandysautonomia may cause emotional instability and has been misdiagnosed as various psychiatric disorders including hysterical neurosis and anorexia nervosa.

- Lupus: various neuropsychiatric symptoms are associated with systemic lupus erythematosus (SLE), including depression. Anorexia and weight loss also may occur with SLE and while rare it may be misdiagnosed as AN.

- Lyme disease is known as the "great imitator", as it may present as a variety of psychiatric or neurologic disorders including anorexia nervosa. "A 12 year old boy with confirmed Lyme arthritis treated with oral antibiotics subsequently became depressed and anorectic. After being admitted to a psychiatric hospital with the diagnosis of anorexia nervosa, he was noted to have positive serologic tests for Borrelia burgdorferi. Treatment with a 14 day course of intravenous antibiotics led to a resolution of his depression and anorexia; this improvement was sustained on 3 year follow-up." Serologic testing can be helpful but should not be the sole basis for diagnosis. The Centers for Disease Control (CDC) issued a cautionary statement (MMWR 54;125) regarding the use of several commercial tests. Clinical diagnostic criteria have been issued by the CDC (CDC, MMWR 1997; 46: 531-535).

- Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare genetic disorder characterized by gastrointestinal dysmotility, severe cachexia progressive external ophthalmoplegia, post-prandial emesis (vomiting after eating), peripheral neuropathy, and diffuse leukoencephalopathy. Onset is prior to age 20 in 60% of cases. ""Miss A" was a 21-year-old Indian woman diagnosed as having treatment-resistant anorexia nervosa." It was subsequently proven to be MNGIE

- superior mesenteric artery syndrome (SMA syndrome) "is a gastrointestinal disorder characterized by the compression of the third or transverse portion of the duodenum against the aorta by the superior mesenteric artery resulting in chronic partial, incomplete, acute or intermittent duodenal obstruction". It may occur as a complication of AN or as a differential diagnosis. There have been reported cases of a tentative diagnosis of AN, where upon treatment for SMA syndrome the patient is asymptomatic.

- Addison's disease is a disorder of the adrenal cortex which results in decreased hormonal production. Addison's disease, even in subclinical form, may mimic many of the symptoms of anorexia nervosa.

- Brain tumors: There are multiple cases were the neuropsychiatric symptoms of a brain tumor were attributed to AN, resulting in misdiagnosis. The tumors in these cases were noted in various regions of the brain including the medulla oblongata, hypothalamus, pituitary gland, pineal gland and the obex.

- Simmond's disease (organic hypopituitarism) – "A 20-year-old Japanese man with a hypothalamic tumor which caused hypopituitarism and diabetes insipidus was mistakenly diagnosed as anorexia nervosa because of anorexia, weight loss, denial of being ill, changes in personality, and abnormal behavior resembling the clinical characteristics of anorexia nervosa"

- Brain calcification either dystrophic calcification or metastatic calcification can present with neuropsychiatric symptoms including those associated with AN and comorbid disorders such as obsessive compulsive disorder.

- cysts that occur in the central nervous system such as dermoid cysts and arachnoid cysts can cause neuropsychiatric symptoms including psychosis.

- Celiac disease is an inflammatory disorder triggered by peptides from wheat and similar grains which cause an immune reaction in the small intestine. "information on the role of the gastrointestinal system in causing or mimicking eating disorders is scarce."(Leffler DA "et al.")

- Gall bladder disease which may be caused by inflammation, infection, gallstones, obstruction of the gallbladder or torsion of the gall bladder – Many of the symptoms of gall bladder disease may mimic anorexia nervosa (AN). Laura Daly, a woman from Missouri, suffered from an inherited disorder in which the gall bladder was not properly attached; the resultant complications led to multiple erroneous diagnoses of AN. Upon performance of a CCK test, standard imaging techniques are done with the patient lying prone, in this instance it was done with the patient in an upright position. The gall bladder was shown to be in an abnormal position having flipped over the liver. The gallbladder was removed and the patient has since recovered. The treatment was performed by William P. Smedley in Pennsylvania.

- colonic tuberculosis misdiagnosed as anorexia nervosa in a physician at the hospital where she worked – "This patient, who had severe wasting, was misdiagnosed as having anorexia nervosa despite the presence of other symptoms suggestive of an organic disease, namely, fever and diarrhea"(Madani, A 2002).

- Crohn's disease: "We report three cases of young 18 to 25 year-old girls, initially treated for anorexia nervosa in a psychiatric department. Diagnosis of Crohn's disease was made within 5 to 13 years."(Blanchet C, Luton JP. 2002)"This disease should be diagnostically excluded before accepting anorexia nervosa as final diagnosis". (Wellmann W "et al.")

- hypothyroidism, hyperthyroidism, hypoparathyroidism and hyperparathyroidism may mimic some of the symptoms of, can occur concurrently with, be masked by or exacerbate an eating disorder and/or various comorbid disorders such as anxiety and depression.

- Insulinomas are (pancreatic tumors) that cause an overproduction of insulin, causing hypoglycemia. Various neurological deficits have been ascribed to this condition including misdiagnosis as an eating disorder.

- Multiple sclerosis (encephalomyelitis disseminata) is a progressive autoimmune disorder in which the protective covering (myelin sheath) of nerve cells is damaged as a result of inflammation and resultant attack by the bodies own immune system. In its initial presentation, MS has been misdiagnosed as an eating disorder.

Drunkorexia is a colloquialism for self-imposed starvation or binge eating/purging combined with alcohol abuse. The term is generally used to denote the utilisation of extreme weight control methods (such as the aforementioned starvation or purging) as a tool to compensate for planned binge drinking.

Research on the combination of an eating disorder and binge drinking has primarily focused on the patterns of college-aged women, but the phenomenon has also been noted among young men. Studies show that college students engage in this combination of self-imposed malnutrition and binge drinking to avoid weight gain from alcohol. A study by the University of Missouri found that 30% of female college students admitted that within the last year they had restricted food in order to consume greater quantities of alcohol. The same study found that men are more likely engage in similar behavior in order to save money for purchasing alcohol. According to the study, 67% of students who restrict calories prior to alcoholic beverage consumption do so to prevent weight gain, while 21% did so to facilitate alcohol intoxication.

According to the Eating Disorder Center of Denver, of the participating college-aged females in an adjunct research study, about 75% met the criteria for alcohol abuse.

'Showbuzz', a CBS news site, has broadcast that, "Drunkorexia is a media coined term reflecting an alarmingly real trend among young women. The non-medical slang term refers to women who choose to eat less so they can party without gaining weight."

R. Andrew Chambers, MD, Assistant Professor, Institute of Psychiatric Research and Director, Laboratory for Translational Neuroscience of Dual Diagnosis Disorders notes that many celebrity blog sites report similar patterns of behavior among young actresses such as Lindsay Lohan and Paris Hilton, and that the condition could be mimicked within the entertainment industry and contemporary youth culture at large.

A few of the medical and psychological conditions that have been known to be associated with this disorder include:

- Gastrointestinal motility disorders

- Oral-motor dysfunction

- Failure to thrive

- Prematurity

- Food allergies

- Sensory problems

- Reflux

- Feeding tube placement

A child that is suffering from malnutrition can have permanently stunted mental and physical development. Getting treatment early is essential and can prevent many of the complications. They can also develop further eating disorders later in life such as anorexia nervosa, or they could become a limited eater—though they could still be a healthy child they may become a picky eater.

Wannarexia, or anorexic yearning,

is a label applied to someone who claims to have anorexia nervosa, or wishes they did, but does not. These individuals are also called wannarexic, “wanna-be ana” or "anorexic wannabe". The neologism "wannarexia" is a portmanteau of the latter two terms. It may be used as a pejorative term.

Wannarexia is a cultural phenomenon and has no diagnostic criteria, although some wannarexics may be instead diagnosed with eating disorder not otherwise specified (EDNOS). Wannarexia is more commonly, but not always, found in teenage girls who want to be trendy, and is likely caused by a combination of cultural and media influences.

Dr. Richard Kreipe states that the distinction between anorexia and wannarexia is that anorexics aren't satisfied by their weight loss, while wannarexics are more likely to derive pleasure from weight loss. Many people who actually suffer from the eating disorder anorexia are angry, offended, or frustrated about wannarexia.

Wannarexics may be inspired or motivated by the pro-anorexia, or pro-ana, community that promotes or supports anorexia as a lifestyle choice rather than an eating disorder. Some participants in pro-ana web forums only want to associate with "real anorexics" and will shun wannarexics who only diet occasionally, and are not dedicated to the "lifestyle" full-time. Community websites for anorexics and bulimics have posted advice to wannarexics saying that they don't want their "warped perspectives and dangerous behaviour to affect others."

Kelsey Osgood uses the label in her book "How To Disappear Completely: On Modern Anorexia" where she describes wannarexia as “a gateway drug for teenagers”.

Exercise bulimia is a subset of the psychological disorder called bulimia in which a person is compelled to exercise in an effort aimed at burning the calories of food energy and fat reserves to an excessive level that negatively affects their health. The damage normally occurs through not giving the body adequate rest for athletic recovery compared to their exercise levels, leading to increasing levels of disrepair. If the person eats a normally healthy and adequate diet but exercises in levels they know require higher levels of nutrition, this can also be seen as a form of anorexia.

Although body dissatisfaction has been found in males as young as age six, muscle dysmorphia's onset is estimated at usually between ages 18 and 20. According to American psychiatry's "DSM-5", muscle dysmorphia is indicated by the diagnostic criteria for body dysmorphic disorder via "the idea that his or her body build is too small or insufficiently muscular", and this specifier holds even if the individual is preoccupied with other body areas, too, as is often the case.

Psychologists have identified further clinical features of muscle dysmorphia, such as excess engagement in activities to increase muscularity, activities such as dietary restriction, over-exercise, and injection of growth-enhancing drugs. Persons experiencing muscle dysmorphia generally spend over three hours daily pondering increased muscularity, and feel unable to limit their weightlifting activities. As in anorexia nervosa, the reverse quest in muscle dysmorphia can be insatiable. They closely monitor their bodies and camouflage by wearing multiple clothing layers to appear larger.

Muscle dysmorphia involves severe distress at having one's body viewed by others. Occupational and social functioning are impaired, and dietary regimes may interfere. They often avoid activities, people, and places to conceal their perceived deficiency of size or muscularity. Roughly half of patients have poor or no insight that these perceptions are unrealistic. Patient histories reveal elevated rates of diagnoses of other mental disorders, including eating disorders, mood disorders, anxiety disorders, and substance use disorder. And rates of suicide attempts are elevated.

Anorexia mirabilis literally means "miraculous lack of appetite". It refers almost exclusively to women and girls of the Middle Ages who would starve themselves, sometimes to the point of death, in the name of God. The phenomenon is also known by the name inedia prodigiosa ("prodigious fasting").