Anorexia Nervosa

Anorexia nervosa is an eating disorder characterized by a fear of gaining weight, strong desire to be thin, and food restriction, which results in low weight. It is the highest mortality psychiatric illness with a mortality rate of 10%.


Individuals with anorexia nervosa, binge-eating/purging type can binge eat and also purge through self-induced vomiting or the misuse of laxatives, diuretics, or enemas. However, some individuals will not binge eat but will regularly purge after eating small amounts of food. Crossover between the subtypes over the course of the disorder is not uncommon; therefore, subtype description should be used to describe current symptoms rather than longitudinal course.

Criterion A

Restriction of energy intake relative to requirements, leading to a significantly low body weight in the context of age, sex, developmental trajectory, and physical health.

Significantly low weight is defined as a weight that is less than minimally normal or, for children and adolescents, less than that minimally expected.
Criterion B

Intense fear of gaining weight or of becoming fat, or persistent behaviour that interferes with weight gain, even though at a significantly low weight.

Criterion C

Disturbance in the way in which one's bodyweight or shape is experienced, undue influence of body weight or shape on self-evaluation, or persistent lack of recognition of the seriousness of the current low body weight.


  • Restricting type: During the last 3 months, the individual has not engaged in recurrent episodes of binge eating or purging behavior (i.e., self-induced vomiting or the mis use of laxatives, diuretics, or enemas). This subtype describes presentations in which weight loss is accomplished primarily through dieting, fasting, and/or excessive exercise.
  • Binge-eating/purging type: During the last 3 months, the individual has engaged in recurrent episodes of binge eating or purging behavior (i.e., self-induced vomiting or the misuse of laxatives, diuretics, or enemas).
  • In partial remission: After full criteria for anorexia nervosa were previously met. Criterion A (low body weight) has not been met for a sustained period, but either Criterion B (intense fear of gaining weight or becoming fat or behavior that interferes with weight gain) or Criterion C (disturbances in self-perception of weight and shape) is still met.
  • In full remission: After full criteria for anorexia nervosa were previously met, none of the criteria have been met for a sustained period of time.

Severity Specifier

The minimum level of severity is based, for adults, on current body mass index (BMI) (see below) or, for children and adolescents, on BMI percentile. The ranges below are derived from World Health Organization categories for thinness in adults; for children and adolescents, corresponding BMI percentiles should be used. The level of severity may be increased to reflect clinical symptoms, the degree of functional disability, and the need for supervision.

  • Mild: BMI > 17kg/m2
  • Moderate: BMI = 16-16.99 kg/m2
  • Severe: BMI = 15-15.99 kg/m2
  • Extreme: BMI < 15 kg/m2

The SCOFF Questionaire

The SCOFF is a simple 5-question screening questionnaire for anorexia and validated in specialist and primary care setting (sensitivity of 100% and specificity of 90%).[1] Though not diagnostic, a score of 2 or more positive answers should raise your index of suspicion of a case, highlighting need for more detailed history.
  1. S: Do you ever make yourself sick because you feel uncomfortably full?
  2. C: Do you worry you have lost control over how much you eat?
  3. O: Have you recently lost more than one stone [14 pounds/6.4kg] in a 3 month period?
  4. F: Do you believe yourself to be fat when others say you are too thin?
  5. F: Would you say that food dominates your life?
  • Weight loss
  • Hyperactivity
  • Bradycardia
  • Hypotension
  • Brittle hair and nails
  • Dry or yellow skin
  • Cyanotic hands and feet
  • Edema
  • Amenorrhea
  • Sleep disturbance
  • Weakness, fatigue
  • Dizziness
  • Constipation
  • Non-focal abdominal pain
  • Polyuria
  • Cold intolerance
  • To avert potentially irreversible effects on physical growth and development, many children and adolescents require inpatient medical treatment, even when weight loss, although rapid, has not been as severe as that suggesting a need for hospitalization in adult patients
  • Hospitalization should occur before the onset of medical instability as manifested by abnormalities in vital signs:
    • Orthostatic hypotension with an increase in pulse of 20 bpm
    • Drop in standing blood pressure of 20 mmHg
    • Bradycardia <40 bpm
    • Tachycardia >110 bpm
    • Inability to sustain core body temperature
  • Various metabolic and bloodwork disturbances can occur in anorexia nervosa
  • Electrolytes are typically all decreased, resulting in:
    • Hyponatremia
    • Hypophosphatemia
    • Hypomagnesmia
    • Hypokalemia
    • Hypocalcemia
  • Thyroid hormones
    • Decreased
  • Cholesterol
    • Increased
  • Elevated serum amylase[2]
  • Reproductive hormones (e.g. - estrogen)
    • Decreased
  • Growth hormone (GH)
  • Cortisol
  • Gonadotropin releasing hormone (GnRH)
  • Leptin
    • Decreased
  • Refeeding syndrome can occur in significantly malnourished patients when they have a sudden increase in calorie intake.
  • The mechanism is that increased caloric intake leads to increased insulin release, which leads to hypophosphatemia, decreased potassium, and decreased magnesium.
  • This series of metabolic chances can lead to cardiac complications, rhabdomyolysis, and seizures.
  • During the refeeding process, serum glucose may rise, while B1 vitamin thiamine may fall

Once weight-gain has restarted, various forms of psychotherapy have been found to be effective for treatment of anorexia, including:[6][7]

  • Individual therapy (CBT, IPT, and psychodynamic approaches)
  • Group therapy (CBT, IPT, and psychodynamic approaches)
  • Family and couple’s self-help, online resources, 12 step programs

Eating Disorder Guidelines

Guideline Location Year PDF Website
International Comparison (Curr Opin Psychiatry) International 2017 - Link
Canadian Clinical Practice Guidelines (Children and Adolescents) Canada 2020 - Link
National Institute for Health and Care Excellence (NICE) UK 2017 - Link
American Psychiatric Association (APA) USA 2006, 2012 - Guideline (2006)
Guideline Watch (2012)
Quick Reference