Eating Disorders – Diagnosis, Symptoms, and Treatment

What are Eating Disorders?

Eating disorders are a group of psychiatric conditions characterized by an atypical relationship with food. They are defined by their features such as binging, purging, or food restriction.  The most common eating disorders are anorexia nervosa and bulimia nervosa.  Patients with eating disorders often have a history of other psychiatric diagnoses such as generalized anxiety disorder, major depressive disorder, post-traumatic stress disorder, and bipolar 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.

Eating disorders commonly arise during times of personal and social stress. The transition to the teenage years and the change in social expectations with high school is a major trigger for these disorders. The transition from high school to college and from college to the professional world are other less common triggers. 

How Common are Eating Disorders?

The lifetime prevalence of anorexia nervosa is about 0.6% in adult Americans.  In the United States the lifetime prevalence of bulimia nervosa is approximately 1%.  These are likely to be 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 for both disorders and state that symptoms had been occurring for several years before their formal diagnosis.

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

Signs and Symptoms

Clinical features of anorexia nervosa are generally more visible once the condition becomes severe, they 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. In extreme cases, calorie restriction can lead to gradual damage to the muscles of the body including the heart. Vitamin deficiencies can also lead to damage to the digestive tract, nervous system, skin, nails, and hair. 

The clinical features of bulimia nervosa are harder to detect and more easily concealed even when severe, they usually include:

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

In severe cases of bulimia nervosa damage to the teeth and esophagus can occur if vomiting is used to purge food from the body. This damage is difficult to detect unless severe and can lead to extensive cavities, loss of teeth, cancer of the throat, and lifelong acid reflux. Other methods of purging such as excessive exercise can lead to early onset arthritis or damage to the muscles. And the use of laxatives and diuretics for purging can result in electrolyte imbalances that may cause issues with the nervous system and heart.

Binge eating and behaviors to prevent weight gain usually occur at least once a week.  Binge eating is characterized by eating a much larger quantity of food than 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 of behaviors in bulimia nervosa is caloric restriction, binging, then self-induced vomiting and/or the use of laxatives.

Diagnosis

Eating disorders are diagnosed based on criteria set by the Diagnostic and Statistical Manual of Mental Disorders V; a book that acts as the gold-standard for psychiatric diagnoses.  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, feeling that they are larger than they appear to others.

Patients with eating disorders often have laboratory studies performed to evaluate for complications such as dehydration, electrolyte abnormalities, 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 (ECG) 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 antipsychotics such as Zyprexa (olanzapine). Which stimulate appetite and are thought to minimize the distorted sense of body perception.  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 (low potassium).

“Refeeding syndrome” is another concern in severe anorexia. The body uses phosphate to transfer energy around the cells and with starvation, this phosphate is lost in the urine and stool. If large amounts of food are reintroduced this lack of phosphate can make the body unable to process and use the energy within this food. This can lead to severe cardiac problems and is why patients with severe anorexia often require a short period of hospitalization. 

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.

References:

1. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), American Psychiatric Association, Arlington, VA 2013. - https://www.psychiatry.org/psychiatrists/practice/dsm
2. Prum BE Attia E, Walsh BT. Behavioral management for anorexia nervosa. N Engl J Med 2009; 360:500. - https://www.ncbi.nlm.nih.gov/pubmed/19179317
3. Kass AE, Kolko RP, Wilfley DE. Psychological treatments for eating disorders. Curr Opin Psychiatry 2013; 26:549. - https://www.ncbi.nlm.nih.gov/pubmed/24060917