[1] One psychologist found multiple origins of anorexia nervosa in a typical female patient, but primarily sexual abuse and problematic familial relations, especially those of overprotecting parents showing excessive possessiveness over their children.

[4] Anorexia also commonly occurs in athletes who play sports where a low bodyweight is thought to be advantageous for aesthetics or performance, such as dance, gymnastics, running, and figure skating.

[1] A daily low dose of olanzapine (Zyprexa®, Eli Lilly) has been shown to increase appetite and assist with weight gain in anorexia nervosa patients.

[30] Signs and symptoms may be classified in various categories including: physical, cognitive, affective, behavioral and perceptual: Interoception involves the conscious and unconscious sense of the internal state of the body, and it has an important role in homeostasis and regulation of emotions.

[47] Aside from noticeable physiological dysfunction, interoceptive deficits also prompt individuals with anorexia to concentrate on distorted perceptions of multiple elements of their body image.

[69] Zucker et al. (2007) proposed that conditions on the autism spectrum make up the cognitive endophenotype underlying anorexia nervosa and appealed for increased interdisciplinary collaboration.

[80] Neuroendocrine dysregulation: altered signaling of peptides that facilitate communication between the gut, brain and adipose tissue, such as ghrelin, leptin, neuropeptide Y and orexin, may contribute to the pathogenesis of anorexia nervosa by disrupting regulation of hunger and satiety.

[83] Some authors suggest that medical professionals should evaluate the presence of unrecognized celiac disease in all people with an eating disorder, especially if they present any gastrointestinal symptoms, (such as decreased appetite, abdominal pain, bloating, distension, vomiting, diarrhea or constipation), weight loss, or growth failure.

Similarly, scientific experiments conducted using mice have suggested that other mammals exhibit these same behaviors, especially compulsive movement, when caloric restriction is induced,[86] likely mediated by various changes in the neuroendocrine system.

[90][91] Recent research has further expanded this perspective, showing how caloric restriction may be adaptive in volatile or uncertain environment - thus potentially explaining the association between an increased risk to develop anorexia nervosa and adverse childhood experiences.

[54] A complicated symptom profile develops when trauma and anorexia meld; the bodily experience of the individual is changed and intrusive thoughts and sensations may be experienced.

[112][113][114] In the face of constant pressure to be thin, often perpetuated by teasing and bullying, feelings of low self-esteem and self-worth can arise, including the perception that one is not "deserving" of food.

[118] Another online aspect contributing to higher rates of eating disorders such as anorexia nervosa are websites and communities on social media that stress the importance of attainment of body ideals extol.

These communities promote anorexia nervosa through the use of religious metaphors, lifestyle descriptions, "thinspiration" or "fitspiration" (inspirational photo galleries and quotes that aim to serve as motivators for attainment of body ideals).

However, both kinds of patients had distorted body images, implying the possibility of disordered eating and highlighting the need for cultural sensitivity when diagnosing anorexia.

The spread of Western media, fashion, and lifestyle ideals across the globe has begun to shift perceptions and standards of beauty in diverse cultures, contributing to a rise in the incidence of anorexia in places they were once rare in.

[8][135] Amenorrhea was removed for several reasons: it does not apply to males, it is not applicable for females before or after the age of menstruation or taking birth control pills, and some women who meet the other criteria for AN still report some menstrual activity.

[citation needed] The distinction between binge purging anorexia, bulimia nervosa and Other Specified Feeding or Eating Disorders (OSFED) is often difficult for non-specialist clinicians.

[165] The Maudsley model of family therapy is problem focused, and the treatment targets re-establishing regular eating, weight restoration, and the reduction of illness behaviors like purging.

[166] Although this model is recommended by the National Institute of Mental Health (NIMH),[167] critics claim that it has the potential to create power struggles in an intimate relationship and may disrupt equal partnerships.

[194] Anorexia nervosa can have serious implications if its duration and severity are significant and if onset occurs before the completion of growth, pubertal maturation, or the attainment of peak bone mass.

[195][medical citation needed] Complications specific to adolescents and children with anorexia nervosa can include growth retardation, as height gain may slow and can stop completely with severe weight loss or chronic malnutrition.

[197] Anorexia nervosa causes alterations in the female reproductive system; significant weight loss, as well as psychological stress and intense exercise, typically results in a cessation of menstruation in women who are past puberty.

Wernicke encephalopathy, which results from vitamin B1 deficiency, has been reported in patients who are extremely malnourished; symptoms include confusion, problems with the muscles responsible for eye movements and abnormalities in walking gait.

The most common gastrointestinal complications of anorexia nervosa are delayed stomach emptying and constipation, but also include elevated liver function tests, diarrhea, acute pancreatitis, gastroesophageal reflux disease (GERD), difficulty swallowing, and, rarely, superior mesenteric artery syndrome.

[204][205] Delayed stomach emptying, or gastroparesis, often develops following food restriction and weight loss; the most common symptom is bloating with gas and abdominal distension, and often occurs after eating.

[208] It has been suggested that there is an association between mitral valve prolapse and sudden cardiac death, but it has not been proven to be causative, either in patients with anorexia nervosa or in the general population.

For athletes, ritualized activities such as weigh-ins place emphasis on gaining and losing large amounts of weight, which may promote the development of eating disorders among them.

As in the case of women, men are more prone to develop an eating disorder if their occupation or sport emphasizes having a slim physique or lighter weight, like modeling, dancing, horse racing, wrestling, and gymnastics.

Awareness of the condition was largely limited to the medical profession until the latter part of the 20th century, when German-American psychoanalyst Hilde Bruch published The Golden Cage: the Enigma of Anorexia Nervosa in 1978.