Eating disorders

Last updated: October 25, 2021

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Eating disorders are psychological conditions characterized by abnormal eating habits, disturbed body image, and, in most of these disorders, weight loss. Adolescent girls and young women are most commonly affected. Individuals with anorexia nervosa are preoccupied with their weight, body image, and a desire to be thin. Self-imposed restriction of calories, excessive exercising, or purging (e.g., laxative use) result in pronounced and potentially fatal weight loss. Bulimia nervosa is characterized by recurrent binge eating followed by measures to compensate for overeating (e.g., self-induced vomiting) driven by a fixation on body weight and shape. However, the BMI in individuals with bulimia nervosa is typically normal or elevated. Individuals with binge eating disorder have binge eating episodes but do not take measures to control their weight. Unlike in individuals with anorexia nervosa or bulimia nervosa, there is no fixation on body weight and shape, and patients are often overweight. Pica is an eating disorder characterized by the appetite for and ingestion of nonnutritive substances (e.g., hair, clay, mud). First-line treatment for all conditions is cognitive behavioral therapy (CBT). All eating disorders, except for pica, are associated with an increased risk of mood disorders, anxiety disorders, and personality disorders and often have a chronic, relapsing disease course, with various outcomes from complete recovery, symptom fluctuation and relapses to progressive deterioration.

Overview of anorexia nervosa and bulimia nervosa
Anorexia nervosa Bulimia nervosa
  • Multifactorial and not entirely understood
  • Associated with the following:
  • Underweight (BMI < 18.5 kg/m2)
  • Normal or slightly elevated (≥ 18.5 kg/m2)
Key features
  • Body image disturbance, fear of weight gain
  • Significant deliberate reduction in body mass, which includes:
    • Restrictive eating
    • Excessive exercise
    • Purging
  • Recurrent binge eating, followed by compulsive behavior to counteract weight gain
  • Both occur at least once a week over a 3-month period
  • Restricting type
    • No binge eating or purging
    • Weight loss: excessive dieting, exercise, fasting
  • Binge-eating/purging type
Additional clinical features
Management Psychotherapy
Nutritional support

Epidemiology [1][2]


The etiology of anorexia nervosa is multifactorial and not entirely understood. Several factors are thought to contribute to the development of the disease:

Features [3]

  • Significant deliberate reduction in body mass (as measured by BMI) using strategies that include restrictive eating, purging, and excessive exercise
  • Fear of weight gain motivates compensatory behavior that promotes weight loss, even if the patient already has low body weight.
  • Body image disturbance
    • Excessive concern about weight and body shape, despite being considerably underweight
    • Lack of awareness of the seriousness of low body weight


  • Restricting type
    • No binge eating or purging over a 3-month period
    • Suggests weight loss is achieved by excessive dieting, exercise, or fasting
  • Binge-eating/purging type
    • Presence of binge eating or purging over a 3-month period
    • Suggests weight loss is achieved by vomiting, diuretic and laxative abuse, or enemas

Severity based on BMI

  • Patients ≤ 20 years of age: BMI below the 10thpercentile for sex and age is considered the threshold for being underweight. [4]
  • Patients > 20 years of age
    • Mild: BMI 17–18.4 kg/m2
    • Moderate: BMI 16–16.99 kg/m2
    • Severe: BMI 15–15.99 kg/m2
    • Extreme: BMI < 15 kg/m2

Additional clinical features

Diagnostics [4]

Laboratory findings normalize following adequate treatment and weight gain.

Treatment [6]

Refeeding syndrome


Anorexia nervosa is a chronic, relapsing disease course with various outcomes (complete recovery, symptom fluctuation and relapses, progressive deterioration).

Individuals with eating disorders may switch from one disorder to another or show merging of symptoms, especially following treatment of one disorder.

Anorexia nervosa is associated with a high mortality rate because of associated medical complications (e.g., arrhythmia, bradycardia) and the high rate of suicide among individuals with the disease.

The antidepressant bupropion lowers the seizure threshold. It is, therefore, contraindicated in individuals with eating disorders who are at an increased risk of developing seizures secondary to dehydration and electrolyte imbalances!

Epidemiology [2][9]

  • Prevalence
    • Female: 0.3%–1%
    • Men: 0.1%
  • Peak age: 20–24 years of age
  • Sex: > (> 90% of affected individuals are young women)


Features [3]

  • Recurrent binge eating
  • Recurrent compulsive behavior to counteract weight gain
    • Self-induced vomiting after binge eating (most frequent)
    • Laxative abuse
    • Transient starvation periods
    • Other weight-loss measures
  • Binge eating and compulsive compensatory behavior both occur at least once a week over a 3-month period.
  • Sense of self-worth pathologically influenced by the perception of physical appearance (body weight and shape)
  • Binging and purging do not occur exclusively during episodes of anorexia nervosa.

Additional clinical features [10]

Diagnostics [4]



The disease course is chronic with relapses.

Bulimia nervosa can transition to anorexia nervosa and vice versa.

Epidemiology [2]

  • Prevalence: most common eating disorder in adults in the US (∼ 2–5% of general population)
  • Peak age: early adulthood to middle age
  • Sex: >

Etiology [12]

The etiology of binge eating disorder is multifactorial and not entirely understood. For factors, see also “Etiology” in anorexia nervosa above.

  • Genetic factors (family history is common)
  • Strict dieting and having access to preferred binge foods
  • Psychological issues (e.g., poor body self-image, stress, childhood bullying)

Features [3]

  • Recurrent binge eating: eating a portion of food disproportionately larger than what an average individual would eat in a similar time span (e.g., two hours) and under similar circumstances
  • No purging behavior
  • Feeling of lack of control over the amount of food consumed with at least three of the following properties:
    • Eating faster than normal
    • Eating until uncomfortably full
    • Eating large amounts when not hungry
    • Eating alone because of embarrassment regarding eating habits
    • Feeling of disgust and/or guilt after eating
  • Binge eating behavior occurs at least once a week over a 3-month period.

Additional clinical features [12]



  • Chronic, relapsing disease course
  • Increased risk of psychological comorbidities (e.g., depression)

Individuals with binge eating disorder may be experiencing emotional distress about their binge eating, but not about their weight or appearance.

Epidemiology [2]

  • Prevalence: highest in children, during pregnancy, and in individuals with certain psychiatric comorbidities (see “Etiology” below)
  • Sex: =


The etiology is not entirely understood. Pica is associated with:

Features [3]

  • An eating disorder characterized by the appetite for and ingestion of nonnutritive substances (e.g., hair, clay, soil, ice, paint chips)
  • Persistent ingestion of nonnutritive substances for > 1 month that is inappropriate for developmental age and not part of culturally or socially normative practice.



  • The diagnosis of pica should only be made if eating behavior is inappropriate for the patient's developmental age and, in the context of personality or neurocognitive disorders, sufficiently severe to qualify as an additional clinical entity.
  • The diagnosis is not made if the eating behavior is rooted in accepted cultural or social practices.


  • Behavioral interventions and nutritional rehabilitation (first-line)
  • Pharmacotherapy: SSRIs (second-line) [16]
  1. Hudson JI, Hiripi E, Pope HG Jr, Kessler RC. The prevalence and correlates of eating disorders in the National Comorbidity Survey Replication.. Biol Psychiatry. 2007; 61 (3): p.348-58. doi: 10.1016/j.biopsych.2006.03.040 . | Open in Read by QxMD
  2. Eating Disorders. Updated: November 1, 2017. Accessed: October 9, 2020.
  3. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders (DSM–5). undefined. 2013 . doi: 10.1176/appi.books.9780890425596 . | Open in Read by QxMD
  4. Lock J, La Via MC. Practice Parameter for the Assessment and Treatment of Children and Adolescents With Eating Disorders. Journal of the American Academy of Child & Adolescent Psychiatry. 2015; 54 (5): p.412-425. doi: 10.1016/j.jaac.2015.01.018 . | Open in Read by QxMD
  5. Hebebrand J, Wehmeier PM, Remschmidt H. Weight criteria for diagnosis of anorexia nervosa. Am J Psychiatry. 2000; 157 (6): p.1024. doi: 10.1176/appi.ajp.157.6.1024 . | Open in Read by QxMD
  6. Rosen DS. Identification and Management of Eating Disorders in Children and Adolescents. Pediatrics. 2010; 126 (6): p.1240-1253. doi: 10.1542/peds.2010-2821 . | Open in Read by QxMD
  7. Arcelus J et al.. Mortality rates in patients with anorexia nervosa and other eating disorders. A meta-analysis of 36 studies.. Arch Gen Psychiatry. 2011; 68 (7): p.724-31. doi: 10.1001/archgenpsychiatry.2011.74 . | Open in Read by QxMD
  8. Kaye WH, Bulik CM, Thornton L, Barbarich N, Masters K. Comorbidity of Anxiety Disorders With Anorexia and Bulimia Nervosa. Am J Psychiatry. 2004; 161 (12): p.2215-2221. doi: 10.1176/appi.ajp.161.12.2215 . | Open in Read by QxMD
  9. Eating Disorders Among Adults - Bulimia Nervosa. Updated: June 6, 2017. Accessed: June 6, 2017.
  10. Fairburn CG. Risk Factors for Bulimia Nervosa. Arch Gen Psychiatry. 1997; 54 (6): p.509. doi: 10.1001/archpsyc.1997.01830180015003 . | Open in Read by QxMD
  11. Goldbloom DS. Pharmacotherapy of bulimia nervosa. MedGenMed. 1999; 1 (2).
  12. Masheb RM, Grilo CM. Emotional overeating and its associations with eating disorder psychopathology among overweight patients with Binge eating disorder. Int J Eat Disord. 2006; 39 (2): p.141-146. doi: 10.1002/eat.20221 . | Open in Read by QxMD
  13. Wilson GT, Wilfley DE, Agras WS, Bryson SW. Psychological Treatments of Binge Eating Disorder. Arch Gen Psychiatry. 2010; 67 (1): p.94. doi: 10.1001/archgenpsychiatry.2009.170 . | Open in Read by QxMD
  14. Quilty LC, Allen TA, Davis C, Knyahnytska Y, Kaplan AS. A randomized comparison of long acting methylphenidate and cognitive behavioral therapy in the treatment of binge eating disorder. Psychiatry Res. 2019; 273 : p.467-474. doi: 10.1016/j.psychres.2019.01.066 . | Open in Read by QxMD
  15. Singhi S, Singhi P, Adwani GB. Role of Psychosocial Stress in the Cause of Pica. Clin Pediatr (Phila). 1981; 20 (12): p.783-785. doi: 10.1177/000992288102001205 . | Open in Read by QxMD
  16. Bhatia MS, Gupta R. Pica responding to SSRI: An OCD spectrum disorder?. The World Journal of Biological Psychiatry. 2009; 10 (4-3): p.936-938. doi: 10.1080/15622970701308389 . | Open in Read by QxMD

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