Anorexia Nervosa

Definition of Anorexia Nervosa


Anorexia nervosa is a psychiatric illness associated with an eating disorder resulting in low body weight and body image distortion with an obsessive fear of gaining weight. Individuals with anorexia are known to control body weight through the means of voluntary starvation, purging, vomiting, excessive exercise, or other weight control measures, such as diet pills or diuretic drugs. Ninety per cent of affected people are female. This is a complex condition, involving psychological, neurobiological, and sociological components.

The term anorexia is of Greek origin (α, k prefix of negation – and orexis appetite) thus meaning a lack of desire to eat. A person who is diagnosed with anorexia is most commonly referred to as anorexic. “Anorexia nervosa” is frequently shortened toanorexia. This is incorrect, as the term “anorexia” used separately refers to the medical symptom of reduced appetite which is distinguishable from anorexia nervosa in being non-psychiatric.

Anorexia Nervosa

Photo of two young women with anorexia.

The diagnosis is based on a combination of behaviour, reported beliefs and experiences, and physical characteristics of the patient. Anorexia is typically diagnosed by a clinical psychologist, psychiatrist or other suitably qualified clinician. The criteria for the diagnosis of anorexia nervosa are:-

A. Refusal to maintain body weight at or above a minimally normal weight for age and height (e.g., weight loss leading to maintenance of body weight less than 85% of that expected; or failure to make expected weight gain during period of growth, leading to body weight less than 85% of that expected).

B. Intense fear of gaining weight or becoming fat, even though underweight.

C. Disturbance in the way in which one’s body weight or shape is experienced, undue influence of body weight or shape on self-evaluation, or denial of the seriousness of the current low body weight.

D. Women with anorexia typically exhibit amenorrhoea (absent periods).

Prevalence of Anorexia Nervosa

The incidence is around eight per 100,000 persons per year.

An upward trend has been observed in the incidence of anorexia in the past century till the 1970s. The most substantial increase was among females aged 15-24 years, for whom a significant increase was observed from 1935 to 1999. The average prevalence rates for anorexia and bulimia nervosa among young females are 0.3 and 1%, respectively. Only a minority of people with eating disorders, especially with bulimia nervosa, are treated in mental healthcare.0605

The majority of research into the prevalence of this condition has been done in Western industrialized countries, so results are generally not applicable outside these areas.

Cases of AN were identified as those individuals who met full DSM-IV criteria by means of clinical interview of the Swedish Twin Registry, who had a hospital discharge diagnosis of AN, or who had a cause-of-death certificate including an AN diagnosis. The overall prevalence of AN was 1.20% and 0.29% for female and male participants, respectively.0604

General-practice studies have shown that the overall incidence rates of anorexia  remained stable during the 1990s, compared with the 1980s. Some evidence suggests that the occurrence of bulimia nervosa is decreasing.

Anorexia is a common disorder among young white females, but is extremely rare among black females. Recent studies confirm previous findings of the high mortality rate within the anorexia population.

Complications Associated with Anorexia Nervosa

In children and adolescents, this remains a serious cause of morbidity and mortality0501 which may result in premature death or life-long medical and psychosocial morbidity. This condition can cause significant medical complications in every organ system of the growing and developing body. Although many of these medical complications improve with nutritional rehabilitation and recovery from the disorder some are potentially irreversible.0701

Anorexia can put a serious strain on many of the body’s organs and physiological resources, particularly on the structure and function of the heart and cardiovascular system, with slow heart rate (bradycardia). People with anorexia  typically have a disturbed electrolyte balance. Those who develop anorexia before adulthood may suffer stunted growth and subsequent low levels of essential hormones (including sex hormones) and chronically increased cortisol levels. Osteoporosis can also develop as a result of anorexia in 38-50% of cases,0702 as poor nutrition leads to the retarded growth of essential bone structure and low bone mineral density. Possible contributors to low BMD in anorexia include hypoestrogenism and hypoandrogenism, undernutrition with decreased lean body mass.

Changes in brain structure and function are early signs of the condition. Enlargement of the ventricles of the brain is thought to be associated with starvation, and is partially reversed when normal weight is regained.9001 Anorexia is also linked to reduced blood flow in the temporal lobes, although since this finding does not correlate with current weight, it is possible that it is a risk trait rather than an effect of starvation.0502

Anorexia Nervosa

Photos of a women with anorexia nervosa.


associated symptoms

  • Decreased libido.
  • Thinning of the hair
  • Constantly feeling “cold”
  • Pallid complexion and sunken eyes
  • Constipation
  • Dry skin
  • Poor circulation, resulting in common attacks of ‘pins and needles’ and purple extremities
  • Headaches
  • Brittle fingernails
  • Bruising easily
  • Distorted body image
  • Poor insight
  • Self-evaluation largely, or even exclusively, in terms of their shape and weight
  • Pre-occupation or obsessive thoughts about food and weight
  • Perfectionism
  • Obsessive compulsive disorder
  • Belief that control over food/body is synonymous with being in control of one’s life
  • Refusal to accept that one’s weight is dangerously low even when it could be life threatening
  • Low self-esteem
  • Intense fear about becoming overweight
  • Clinical depression or chronically low mood
  • Withdrawal from previous friendships and other peer-relationships
  • Deterioration in relationships with the family
  • Denial of basic needs, such as food and sleep
  • Excessive exercise, food restriction
  • Secretive about eating or exercise behaviour
  • Fainting
  • Self-harm
  • Very sensitive to references about body weight
  • Aggressive when forced to eat “forbidden” foods

The distinction between the diagnoses of anorexia nervosa, bulimia nervosa and eating disorder not otherwise specified is often difficult and there is considerable overlap between patients diagnosed with these conditions.


There is no single cause for anorexia; it arises from a mixture of social, psychological and biological factors.

Current research is commonly focused on explaining existing factors and uncovering new causes. However, there is considerable debate over how much each of the known causes contributes to the development of anorexia. In particular, the contribution of perceived media pressure on women to be thin has been especially contentious.9601

Genetic: Family and twin studies have suggested that genetic factors contribute to about 50% of the variance for the development of an eating disorder0101 and that anorexia shares a genetic risk with clinical depression.0001 This evidence suggests that genes influencing both eating regulation, and personality and emotion, may be important contributing factors.

Picture of young woman with anorexia .

Serotonin: There are strong correlations between the neurotransmitter serotonin (brain chemical) and various psychological symptoms such as mood, sleep, emesis (vomiting), sexuality and appetite. A recent review of the scientific literature has suggested that anorexia is linked to a disturbed serotonin system.0503 There is evidence that both personality characteristics including anxiety and perfectionism and disturbances to the serotonin system are still apparent after patients have recovered from anorexia,0504 suggesting that these disturbances are likely to be causal risk factors.

Zinc deficiency causes a decrease in appetite that can degenerate in anorexia (AN), appetite disorders and, notably, inadequate zinc nutriture. The use of zinc has been advocated since 1979 by Bakan. At least five trials showed that zinc improved weight gain in anorexia. A 1994 randomized, double-blind, placebo-controlled trial showed that zinc (14 mg per day) doubled the rate of body mass increase in the treatment of AN.0002

Deficiency of other nutrients such as tyrosine and tryptophan (precursors of the monoamine neurotransmitters norepinephrine and serotonin, respectively), as well as vitamin B1 (thiamine) could contribute to this phenomenon of malnutrition-induced malnutrition.0002

Over-estimate the size or fatness of their own bodies: One of the most well-known findings is that people with anorexia tend to over-estimate the size or fatness of their own bodies. A recent review of research in this area suggests that this is not a perceptual problem, but one of how the perceptual information is evaluated by the affected person.0102

Recent research suggests people with anorexia nervosa may lack a type of overconfidence bias in which the majority of people feel themselves more attractive than others would rate them. In contrast, people with anorexia nervosa seem to more accurately judge their own attractiveness compared to unaffected people, meaning that they potentially lack this self-esteem boosting bias.0601

Personality traits: People with this condition have been found to have certain personality traits that are thought to predispose them to develop eating disorders. High levels of obsessionality, restraint, and clinical levels of perfectionism, have been cited as commonly reported factors in research studies.0504

Psychological difficulties: It is often the case that other psychological difficulties and mental illnesses exist alongside anorexia nervosa in the sufferer. Clinical depression, obsessive compulsive disorder, substance abuse and one or more personality disorders are the most likely conditions to be present with anorexia nervosa, and high-levels of anxiety and depression are likely to be present regardless of whether they fulfill diagnostic criteria for a specific syndrome.0401

Research into the neuropsychology of anorexia has indicated that many of the findings are inconsistent across studies and that it is hard to differentiate the effects of starvation on the brain from any long-standing characteristics. Nevertheless, one reasonably reliable finding is that those with anorexia have poor ability to change past patterns of thinking.0402

Other studies have suggested that there are some attention and memory biases that may maintain anorexia.0507Attentional biases seem to focus particularly on body and body-shape related concepts, making them more salient for those affected by the condition.

Cultural Factors: Sociocultural studies have highlighted the role of cultural factors, such as the promotion of thinness as the ideal female form in Western industrialised nations, particularly through the media. A recent epidemiological study of 989,871 Swedish residents indicated that gender, ethnicity and socio-economic status were large influences on the chance of developing anorexia, with those with non-European parents among the least likely to be diagnosed with the condition, and those in wealthy, white families being most at risk.0301 Those professions where there is a particular social pressure to be thin, such as models and dancers, were more likely to develop anorexia during the course of their career,8001 and further research indicates that those with anorexia have much higher contact with cultural sources that promote weight-loss.9401

Western Media: Although anorexia nervosa is usually associated with Western cultures, exposure to Western media is thought to have led to an increase elsewhere.0201

Sexual abuse: There is a high rate of child sexual abuse experiences in those who have been diagnosed with anorexia. Although prior sexual abuse is not thought to be a specific risk factor for anorexia, although it is a risk factor of mental illness in general, those who have experienced such abuse are more likely to have more serious and chronic symptoms.0602

Statistics and Prognosis

Anorexia statistics provide reason for concern.

  • Even with treatment, 2 – 3% of people with anorexia die.
  • 60% of anorexics make a full recovery.

It is associated with a substantial risk of death and suicide. Mortality rate in long term studies is 15-20%. Most deaths result from suicide or direct medical complications. Features correlated with fatal outcome are longer duration of illness, binging and purging, comorbid substance abuse, and comorbid affective disorders.0003 Our meta-analysis shows that suicide among patients with anorexia nervosa is more frequent when compared with the general population.0403


Weight Gain: The primary focus is on weight gain as quickly as possible, especially with those who have particularly serious conditions that require hospitalization. This may be done as an involuntary hospital treatment under mental health lawIn particularly serious cases, . In the majority of cases, however, people with anorexia are treated as outpatients, with input from physicians, psychiatrists, clinical psychologists and other mental health professionals.

The results in two trials suggested that ‘treatment as usual’ or similar may be less efficacious than a specific psychotherapy. No specific treatment was consistently superior to any other specific approach. Dietary advice as a control arm had a 100% non-completion rate in one trial. No specific approach can be recommended from this review. It is unclear why ‘treatment as usual’ performed so poorly or why dietary advice alone appeared so unacceptable as the reasons for non-completion were not reported. There is an urgent need for large well-designed trials in his area.0302

Family therapy has also been found to be an effective treatment for adolescents with anorexia.0508 Studies at The Maudsley show that the majority of patients, even those who are severely ill, can be treated quite successfully as outpatients provided that the parents participate in treatment. In this family-based treatment, parents are viewed as a resource rather than a hindrance. Optimism regarding these encouraging findings should be tempered until larger scale randomized trials have been conducted.0509 A short course of family therapy is as effective as a longer course at follow-up.0609

Drug treatments, such as SSRI or other antidepressant medication, have not been found to be generally effective for either treating anorexia,0606 or preventing relapse.0607

Supplementation with 14mg/day of zinc is recommended as routine treatment for anorexia nervosa due to a study showing a doubling of weight regain after treatment with zinc was begun. The mechanism of action is hypothesized to be an increased effectiveness of neurotransmission in various parts of the brain after adequate zinc intake begins resulting in increased appetite.0608

Oral estrogen administered as HRT preparations have not been shown to increase bone mineral density or prevent bone loss in anorexia nervosa.0004, 0610This is surprising as HRT is effective in increasing bone density in most other situations. The possible benefits of other routes of HRT administration such as the patch or oestrogen at contraceptive levels either administered orally or as a patch has not been investigated. Other potential benefits of hormone replacement such as heart protection have not been studied to date but the benefits of HRT in general particularly for young women who are oestrogen hormone deficient are likely to pertain.



For years, author Jennifer Schaefer lived with both anorexia and bulimia. She credits her successful recovery to the technique she learned from her psychologist, Thom Rutledge.

This groundbreaking book illustrates Rutledge’s technique. As in the author’s case, readers are encouraged to think of an eating disorder as if it were a distinct being with a personality of its own. Further, they are encouraged to treat the disorder as a relationship rather than as a condition. Schaefer named her eating disorder Ed; her recovery involved “breaking up” with Ed

  • Shares the points of view of both patient and therapist in this approach to treatment
  • Helps people see the disease as a relationship from which they can distance themselves
  • Techniques to defeat negative thoughts that plague eating disorder patients

Prescriptive, supportive, and inspirational,Life Without Ed shows readers how they too can overcome their eating disorders.


Related Medical Abstracts

Anorexia Nervosa Support Groups

The Internet has enabled anorexics and bulimics to contact and communicate with each other outside of a treatment environment, with much lower risks of rejection by mainstream society. A variety of websites exist, some run by sufferers, some by former sufferers, and some by professionals. The majority of such sites support a medical view of anorexia as a disorder to be cured, although some people affected by anorexia reject the medical view and argue that anorexia is a ‘lifestyle choice’, using the internet for mutual support, and to swap weight-loss tips.0603There are various non-profit and community groups that offer support and advice to people who suffer from anorexia or who care for someone who does. Several are listed in the links below and may provide useful information for those wanting more information or help on treatment and medical care.

This page was updated 1st July 2008

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