> Table of Contents > Anorexia Nervosa
Anorexia Nervosa
Umer Farooq, MD, MBBS
Wajiha Illyas, MD
image BASICS
  • Restriction of energy intake leading to significantly low weight in the context of age, sex, developmental trajectory, and physical health, with intense fear of weight gain and body image disturbance. Significantly low weight is defined as weight that is less than minimally normal/expected.
  • Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5), divides anorexia into two types:
    • Restricting type: not engaged in binge eating or purging behaviors for last 3 months
    • Binge eating/purging type: regularly engages in binge eating or purging behaviors (last 3 months)
  • System(s) affected: cardiovascular, endocrine, metabolic, gastrointestinal, nervous, reproductive
  • Severity of anorexia nervosa (AN) is based on BMI (per DSM-5):
    • Mild: BMI ≥ 17 kg/m2
    • Moderate: BMI 16 to 16.99 kg/m2
    • Severe: BMI 15 to 15.99 kg/m2
    • Extreme: BMI <15 kg/m2
  • Predominant age: 13 to 20 years
  • Predominant sex: female > male (10:1 female-to-male ratio)
  • 8 to 19 women/2 men per 100,000 per year
  • 0.4% in women
  • Less is known; however, an estimate suggests 0.3% in men (higher in gay and bisexual men).
  • Complex relationship among genetic, biologic, environmental, psychological, and social factors that result in the development of this disorder
  • Subsequent malnutrition may lead to multiorgan damage.
  • Serotonin, norepinephrine, and dopamine neuronal systems are implicated.
  • Underlying genetic vulnerability is likely but not well understood, some evidence of higher concordance rates in monozygotic twins than in dizygotic
  • First-degree female relative with eating disorder increases risk 6- to 10-fold.
  • Female gender
  • Adolescence
  • Body dissatisfaction
  • Perfectionism
  • Negative self-evaluation
  • Academic pressure
  • Severe life stressors
  • Participation in sports or artistic activities that emphasize leanness or involve subjective scoring: ballet, running, wrestling, figure skating, gymnastics, cheerleading, weight lifting
  • Type 1 diabetes mellitus
  • Family history of substance abuse, affective disorders, or eating disorder
Prevention programs can reduce risk factors and future onset of eating disorders (1)[A]:
  • Target adolescents and young women 15 years of age or older.
  • Encourage realistic and healthy weight management strategies and attitudes.
  • Promote self-esteem.
  • Reduce focus on thin as ideal.
  • Decrease co-occurring anxiety/depressive symptoms and improve stress management.
  • Mood disorder (major depression)
  • Social phobia, obsessive-compulsive disorder
  • Substance abuse disorder
  • High rates of cluster C personality disorders
  • May be normal
  • Abnormal vital signs: hypothermia, bradycardia, orthostatic hypotension
  • Body weight <85% of expected
  • Cardiac: dysrhythmias, midsystolic click of mitral valve prolapse
  • Skin/extremities: dry skin; lanugo hair on extremities, face, and trunk; hair loss; edema
  • Neurologic and abdominal exams: to rule out other causes of weight loss and vomiting
  • Hyperthyroidism, adrenal insufficiency
  • Inflammatory bowel disease, malabsorption
  • Immunodeficiency, chronic infections
  • Diabetes
  • CNS lesion
  • Bulimia, body dysmorphic disorder
  • Depressive disorders with loss of appetite
  • Anxiety disorder, food phobia
  • Conversion disorder
  • Psychological self-report screening tests may be helpful, but diagnosis is based on meeting the DSM-5 criteria.
  • Most findings are related directly to starvation and/or dehydration. All findings may be within normal limits.
  • Screening tools:
    • SCOFF questionnaire (2)[B]
    • Eating Disorder Screen for Primary Care
Initial Tests (lab, imaging)
  • CBC: anemia, leukopenia, thrombocytopenia
  • Low serum luteinizing hormone, follicle-stimulating hormone; low serum testosterone in men
  • Thyroid function tests: low thyroid-stimulating hormone with normal T3/T4
  • Liver function tests: abnormal liver enzymes
  • Chem 7: altered BUN, creatinine clearance; electrolyte disturbances
  • Hypoglycemia, hypercholesterolemia, hypercortisolemia, hypophosphatemia
  • Low sedimentation rate
  • 12-Lead electrocardiogram to assess for prolonged QT interval
  • Dual-energy x-ray absorptiometry of bone to assess for diminished bone density, only if underweight for >6 months
Test Interpretation
  • Osteoporosis/osteopenia, pathologic fractures
  • Sick euthyroid syndrome
  • Cardiac impairment
  • Initial treatment goal geared to weight restoration; most managed as outpatients (OPs)
  • OP treatment:
    • Interdisciplinary team (primary care physician, mental health provider, dietician)
    • Average weekly weight gain goal: 0.5 to 1.0 kg, with stepwise increase in calories
    • Cognitive-behavioral therapy (CBT), interpersonal psychotherapy, family-based therapy
    • Focus on health, not weight gain alone.
    • Build trust and a treatment alliance.
    • Involve the patient in establishing diet and exercise goals.
    • Challenge fear of uncontrolled weight gain; help the patient to recognize feelings that lead to disordered eating.
    • In chronic cases, goal may be to achieve a safe weight rather than a healthy weight.
  • Inpatient treatment:
    • If possible, admit to a specialized eating disorders unit.
    • Assess risk for refeeding syndrome (metabolic shift from a catabolic to anabolic state).
    • Monitor vital signs, electrolytes, cardiac function, edema, and weight gain.
    • Initial supervised meals may be necessary.
    • Stepwise increase in activity
    • Tube feeding or total parenteral nutrition is used only as a last resort.
    • Supportive symptomatic care as needed
  • P.63

  • Most patients should be treated as OPs using an interdisciplinary team.
  • Behavioral therapies (e.g., cognitive-behavioral, interpersonal, or family therapy) should be offered (3,4,5)[A].
  • CBT has demonstrated effectiveness as a means of improving treatment adherence and minimizing dropout among patients with AN (6)[A].
First Line
  • No medications are available that effectively treat patients with AN, but pharmacotherapy may be used as an adjuvant to CBTs (5,7)[A].
  • If medications are used, start with low doses due to increased risk for adverse effects.
  • SSRIs may:
    • Help to prevent relapse after weight gain
    • Treat comorbid depression or obsessive-compulsive disorder.
    • Use of atypical antipsychotics is being studied with mixed findings to date. Olanzapine is potentially beneficial as an adjuvant treatment of underweight individuals in the inpatient settings.
  • Attend to black box warnings concerning antidepressants.
Second Line
  • Management of osteopenia:
    • Primary treatment is weight gain.
    • Elemental calcium 1,200 to 1,500 mg/day plus vitamin D 800 IU/day
    • No indication for bisphosphonates in AN
    • Weak evidence for use of hormone-replacement therapy
  • Psyllium (Metamucil) preparations to prevent constipation
Patients with AN require an interdisciplinary team (primary care physician, mental health provider, nutritionist). An important step in management is to arrange OP mental health therapist.
Admission Criteria/Initial Stabilization
  • Suggested physiologic values: heart rate <40 beats/min, BP <90/60 mm Hg, symptomatic hypoglycemia, potassium <3 mmol/L, temperature <97.0°F (36.1°C), dehydration, other cardiovascular abnormalities, weight <75% of expected, rapid weight loss, lack of improvement while in OP therapy
  • Suggested psychological indications: poor motivation/insight, lack of cooperation with OP treatment, inability to eat, need for nasogastric feeding, suicidal intent or plan, severe coexisting psychiatric disease, problematic family environment
Pediatric Considerations
  • Children often present with nausea, abdominal pain, fullness, and inability to swallow.
  • Additional indications for hospitalization: heart rate <50 beats/min, orthostatic BP, hypokalemia or hypophosphatemia, rapid weight loss even if weight not <75% below normal
  • Children and adolescents should be offered family-based treatment.
Geriatric Considerations
Late-onset AN (>50 years of age) may be long-term disease or triggered by death of loved one, marital discord, or divorce.
Discharge Criteria
Discharge when medically stable. Arrange OP appointment with mental health provider and primary care provider.
  • Close follow-up until patient demonstrates forward progress in care plan
  • Family and individual therapy is extremely important for the long-term benefits/outcomes.
  • CBT is very helpful for the treatment of AN and may be helpful for the prevention of relapse.
  • Emphasize importance of moderate activity for health, not thinness.
Patient Monitoring
  • Level of exercise activity
  • Weigh weekly until stable, then monthly
  • Depression, suicidal ideation
  • Dietary consultation while patient is hospitalized.
  • Nutritional education programs
  • Provide patients and families with information about the diagnosis and its natural history, health risks, and treatment strategies.
  • http://www.mayoclinic.org/diseases-conditions/anorexia/home/ovc-20179508
  • The National Alliance on Mental Illness: http://www.nami.org/Learn-More/Mental-Health-Conditions/Eating-Disorders
  • Prognosis: ˜50% recover, 30% improve, 20% are chronically ill.
  • Outcomes in men are likely better than in women.
  • Mortality: 3%
  • High risk of suicide in patients suffering from AN (8)[A]
1. Stice E, Shaw H, Marti CN. A meta-analytic review of eating disorder prevention programs: encouraging findings. Annu Rev Clin Psychol. 2007;3:207-231.
2. Cotton MA, Ball C, Robinson P. Four simple questions can help screen for eating disorder. J Gen Intern Med. 2003;18(1):53-56.
3. Hay P, Bacaltchuk J, Claudino A, et al. Individual psychotherapy in the outpatient treatment of adults with anorexia nervosa. Cochrane Database Syst Rev. 2003;(4):CD003909.
4. Fisher CA, Hetrick SE, Rushford N. Family therapy for anorexia nervosa. Cochrane Database Syst Rev. 2010;(4):CD004780.
5. Bulik CM, Berkman ND, Brownley KA, et al. Anorexia nervosa treatment: a systematic review of randomized controlled trials. Int J Eat Disord. 2007;40(4):310-320.
6. Galsworthy-Francis L, Allan S. Cognitive behavioural therapy for anorexia nervosa: a systematic review. Clin Psychol Rev. 2014;34(1):54-72.
7. Claudino AM, Hay P, Lima MS, et al. Antidepressants for anorexia nervosa. Cochrane Database Syst Rev. 2006;(1):CD004365.
8. Zerwas S, Larsen JT, Petersen L, et al. The incidence of eating disorders in a Danish register study: associations with suicide risk and mortality. J Psychiatr Res. 2015;65:16-22.
Additional Reading
  • American Psychiatric Association. Practice Guideline for the Treatment of Patients with Eating Disorders. 3rd ed. Arlington, VA: American Psychiatric Association; 2006
  • Dalle Grave R. Eating disorders: progress and challenges. Eur J Intern Med. 2011;22(2):153-160.
  • National Collaborating Centre for Mental Health. Eating Disorders: Core Interventions in the Treatment and Management of Anorexia Nervosa, Bulimia Nervosa and Related Eating Disorders (NICE Guidelines). Leicester, United Kingdom: British Psychological Society; 2004.
See Also
  • Amenorrhea; Osteoporosis; Bulimia Nervosa
  • Algorithm: Weight Loss
  • F50.00 Anorexia nervosa, unspecified
  • F50.01 Anorexia nervosa, restricting type
  • F50.02 Anorexia nervosa, binge eating/purging type
Clinical Pearls
  • “Are you satisfied with your eating patterns?” and/or “Do you worry that you have lost control over how you eat?” may help to screen those with an eating problem.
  • Studies have shown patients with AN will not accept medications unless combined with psychotherapy.
  • To care for a patient with AN, an interdisciplinary team that includes a medical provider, a dietician, and a behavioral health professional is the most accepted approach.
  • Family analysis is necessary for the patients with AN to determine what kind of therapy would be most helpful.
  • 3 months amenorrhea is no longer the criteria needed for the diagnosis of AN.