Eating Disorders

What are Eating Disorders?

Eating disorders are a group of psychiatric conditions characterized by abnormal features such as binging, purging, or food restriction.  The most common eating disorders include anorexia nervosa and bulimia nervosa.  Patients with eating disorders often have coexisting psychiatric diagnoses such as anxiety disorders and major depressive disorder.

Eating disorders may also be complicated by medical conditions such as malnutrition, dehydration, hypokalemia (low potassium), and dental problems.  Severe cases can result in death unless patients are hospitalized.  

What Causes Eating Disorders?

The causes of eating disorders, including anorexia and bulimia nervosa, likely involves a combination of genetic and environmental factors.  Studies in families and twins show a strong genetic association with the disease.

The specific etiology of anorexia nervosa and bulimia nervosa are unclear, however, both these conditions show altered brain structure and function based on current research.  Specifically, experts have found that these diseases are related to abnormal functioning of corticolimbic circuits in the brain, which are important for appetite.

How Common are Eating Disorders?

Eating disorders are relatively common in the United States and are often initially evaluated in primary care clinic.  These diseases frequently require referral to a multidisciplinary team of health care specialists such as psychiatrists, psychologists, and nutritionists.

The lifetime prevalence of anorexia nervosa is about 0.6% in adult Americans.  In the United States and Worldwide, the lifetime prevalence of bulimia nervosa is approximately 1%.  These are likely to be a low estimates as many patients with eating disorders conceal their diagnosis.  Anorexia nervosa and bulimia nervosa are both more frequently seen in women compared to men.  Most patients are diagnosed around age 18 in both disorders.

Signs and Symptoms

Clinical features of anorexia nervosa typically include:

  • Food restriction leading to low body weight
  • Fear of gaining weight and persistent behavior preventing weight gain
  • Distorted body weight and shape perception

Other features may include fear of various foods, preference for low-calorie foods, and obsessive food behaviors.

The clinical features of bulimia nervosa usually include:

  • Binge eating
  • Abnormal behaviors to prevent weight gain
  • Excessive worrying about body weight & shape

Binge eating and behaviors to prevent weight gain usually occur at least once a week.  Bing eating is characterized by eating a significantly more amount of food that most people would eat over a certain time period.  Patients usually feel like they have no control over their eating habits.

Patients often use various strategies to prevent weight gain such as self-induced vomiting, excessive exercise, fasting, and misuse of laxatives and diuretics.  The typical sequence in bulimia nervosa is caloric restriction, binging, then self-induced vomiting.


Eating disorders are diagnosed based on criteria set by the Diagnostic and Statistical Manual of Mental Disorders V.  Bulimia nervosa is diagnosed in patients with repeated occurrences of both binge eating and inappropriate compensatory behavior to prevent weight gain.  This must occur at least 1 day per week for 3 months.

Anorexia nervosa is diagnosed in patients that restrict food intake to lower body weight to unhealthy levels.  These patients have an intense fear of becoming fat and frequently perform behaviors to prevent weight gain despite being underweight.  They also typically have a distorted perception of their body appearance.

Patient with eating disorders often have laboratory studies performed to evaluate for complications such as dehydration, hypokalemia, and nutritional deficiencies.  Commonly ordered blood tests include a CMP (comprehensive metabolic panel), magnesium, phosphorus, prealbumin, PT/INR (coagulation studies), CBC (complete blood cell count), and thyroid function tests (TSH, free T4).

Your doctor may also order vitamin levels such as thiamine, folate, vitamin B12, iron studies, and vitamin D.  Most individuals also provide a urine sample for urinalysis.  An electrocardiogram (EKG) is also usually obtained to evaluate the electrical activity of your heart.

Eating Disorders Medication and Treatment

Treatment of eating disorders often requires involvement of a psychiatrist, primary care physician, and dietician.

Anorexia nervosa treatment usually incorporates psychotherapy and nutritional rehabilitation such as prescribing and supervising the patient’s diet.  Psychotherapy may involve family therapy and cognitive-behavioral therapy.  Patients that do not respond to these measures often require medical treatment with the atypical antipsychotic Zyprexa (olanzapine)Wellbutrin (bupropion) should be avoided as it can increase seizure risk in patients with eating disorders.  Hospitalization is frequently necessary for patients who fail outpatient therapy with the aforementioned strategies or those who have medical complications such as significant dehydration or hypokalemia.

The treatment of bulimia nervosa also includes nutritional rehabilitation, psychotherapy, and pharmacotherapy.  Psychological treatment typically involves cognitive-behavioral therapy.  Patients may also benefit from antidepressants such as selective serotonin reuptake inhibitors (SSRIs).  Prozac (fluoxetine) has shown the greatest benefit amongst SSRIs in studies.


  1. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), American Psychiatric Association, Arlington, VA 2013. -
  2. Prum BE Attia E, Walsh BT. Behavioral management for anorexia nervosa. N Engl J Med 2009; 360:500. -
  3. Kass AE, Kolko RP, Wilfley DE. Psychological treatments for eating disorders. Curr Opin Psychiatry 2013; 26:549. -

Eating Disorders Medication

The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.