Anorexia Nervosa



Anorexia nervosa (AN) is a complex biopsychosocial illness.

  • Diagnostic and Statistical Manual of Mental Disorders 5th edition (DSM-5) criteria:
    • 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 weight that is less than minimally normal or, for children and adolescents, less than minimally expected.
    • Intense fear of gaining weight or becoming fat, or persistent behavior that interferes with weight gain, even though at a significantly low weight
    • 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 persistent lack of recognition of the seriousness of current low body weight
  • Types: restricting (no binge eating or purging) or binge eating/purging (purging includes vomiting, laxatives, and/or diuretic use)
  • Reprinted with permission from the American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 5th ed. Arlington, VA: American Psychiatric Association; 2013:171.


  • Approximately 0.5% of adolescent girls in the United States have AN.
  • 10% of all patients with eating disorders are males.
  • In younger patients, approximately equal numbers of females and males
  • Increasing prevalence of eating disorders is seen in preadolescents, in males, and in minority populations within the United States.

Risk Factors

  • Early physical/pubertal development
  • Personality traits such as perfectionism and eagerness to please
  • Family history of eating disorders, alcoholism, or mood disorders
  • Involvement in sports or activities that emphasize shape/weight
  • “Dieting” itself is a risk factor for developing an eating disorder.


  • Family studies demonstrate that 1st-degree relatives have a 10-fold increased lifetime risk of developing AN.
  • Twin studies also support role of genetics and familial concordance of AN.

General Prevention

  • Assess height, weight, and BMI at every preventive visit at a minimum; evaluate for deviations.
  • Discourage “dieting” behavior. Instead, focus on promoting healthy eating behaviors and lifestyle change.
  • Strongly encourage regular family meals. Research suggests that regular family meals are a protective factor for all types of eating disorders and obesity.


  • Physical manifestations are primarily the result of caloric restriction and consequences of malnutrition, which can affect all organ symptoms. The degree of symptoms seen may be due in part to the duration and severity of caloric restriction.
  • Associated changes may also be due to purging, including vomiting, laxative use, or diet pill use.
  • Bradycardia and hypothermia may result from significantly decreased metabolic rate due to malnutrition and caloric restriction.
  • Hormonal changes due to starvation include resumption of prepubertal gonadotropin secretion.


Evidence for specific etiology is not definitive; most likely multifactorial, including genetic risk factors, environmental triggers, and individual and family life experiences

Commonly Associated Conditions

  • Amenorrhea
  • Osteopenia/osteoporosis
  • Female athlete triad (disordered eating, amenorrhea, osteoporosis)
  • Depression
  • Anxiety disorders including obsessive-compulsive disorder
  • Substance abuse

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