Introduction

This article discusses the three main eating disorders recognized by the Diagnostic and Statistical Manual-Fifth Edition (DSM-V), which are anorexia nervosa, bulimia nervosa, and binge eating disorder.   These fall as being the severest of all eating disorders, although there are many more children, adolescents, and adults with milder eating disorders that don’t quite meet the criteria for a full-blown eating disorder.  Each of these eating disorders will be discussed in detail in this chapter, along with the recommended treatments and complications of each.

Eating Disorders

There three major eating disorders are seen in a family practice or psychiatric setting. These include anorexia nervosa (AN), bulimia nervosa (BN), and binge-eating disorder (BED).  All of these can be life-threatening but for different reasons.

Anorexia nervosa is one of the more threatening eating disorders, mainly found in young women.  It involves an inability to maintain a normal weight due to restricting of foods, an extreme fear of gaining weight, and excessive exercising.  These patients are often malnourished and extremely thin.

Patients with bulimia nervosa may be of normal weight or low weight. They tend to have recurrent episodes of eating large amounts of food over a small period and then engaging in the compensatory behavior, such as purging, fasting, diuretic use, laxative abuse, or excessive exercise.  The patient has an abnormal perception of their body and a serious desire to be thin.

Binge eating disorder is also life-threatening.  It involves eating a large quantity of food over a very short period but not engaging in any compensatory measures, such as purging or excessive exercise.  Of the three, this is the most common eating disorder.  Patients with this disorder are often extremely overweight, but they can be of a more normal weight.

Incidence and Prevalence

Anorexia nervosa is found in many different socioeconomic classes and all developed nations.  It is found, globally,in up to three percent of women and up to 0.3 percent in men.  It is more common among athletes, young women, and those with occupations that are focused on one’s weight and appearance. As many as five percent of women will have subclinical anorexia nervosa but won’t meet the full diagnostic criteria for the disorder.

Bulimia nervosa is somewhat underdiagnosed.  The prevalence of the disorder is believed to be one percent with a lifetime prevalence of 1.5 percent for females and 0.5 percent in males.  About two-thirds of patients with bulimia will have a normal weight or may be overweight.  Only 3-4 percent have a BMI of less than 18.5.

The most common eating disorder is binge-eating disorder or BED.  About 4 percent of adolescent girls will meet the diagnostic criteria for binge eating disorder. When it comes to any eating disorder, it is believed that up to 13 percent of teen girls will develop an eating disorder at some point before the age of 20 years.

Predisposing Factors

Predisposing factors to all eating disorders involve being in an occupation or having hobbies that require thinness or losing weight quickly, such as competitive bodybuilders, runners, gymnasts, wrestlers, ballet dancers, flight attendants, and ice skaters.

Other risk factors include being female (as females are more likely to have any eating disorder), being young (as it tends to start in the teenage years or early adulthood), and having a first-degree relative who also has an eating disorder.  These patients will also have low self-esteem and psychological anxiety that increases the risk of having an eating disorder.

Exposure to media pressure and societal pressure to be thin contribute to getting an eating disorder.  Pressures placed on athletes, models, dancers, and actors place these individuals at a higher risk of having an eating disorder.

Signs and Symptoms

The major signs and symptoms of anorexia nervosa include having restrictive eating patterns, excessive exercise, and having multiple physical findings related to low metabolism and malnutrition.  There will be amenorrhea, dry skin, acrocyanosis, lanugo hair on the body, thinning hair, lack of subcutaneous fat, and evidence of low metabolism (hypotension, bradycardia, and hypothermia).

Patients with bulimia nervosa may have callouses on the dorsum of their hand from sticking their finger down their throat.  They will have evidence of dental enamel erosion. Other signs include evidence of dehydration, such as lightheadedness, dizziness, palpitations, and orthostatic hypotension.  GI symptoms include pharyngeal irritation, abdominal pain, problems swallowing, constipation, and reflux disease.  Amenorrhea occurs in up to 50 percent of women with bulimia, with others having irregular menstrual periods.  There can be EKG changes, such as prolongation of the QT interval, increased P wave amplitude, increased PR interval, depression of the ST segment, and a widening of the QRS interval.

Patients with binge eating disorder may have episodes of eating within a short period of a large quantity of food. There is a lack of control over the amount the patient eats, and they often eat past the point of comfort.  They don’t engage in purging behaviors or excessive exercise and often are overweight.  The binge eating must occur for a minimum of three months to carry the diagnosis of the disorder and must cause a significant degree of psychological distress.

Clinical Presentation

Patients with anorexia nervosa may be anywhere on the spectrum of weight but are often very thin and emaciated.  They attempt to hide their weight loss by wearing bulky clothing or many layers of clothing.  They have the classic vital signs of hypothermia, bradycardia, and hypotension.  Many physical findings are related to malnourishment, such as thinning hair, loss of subcutaneous fat, dry skin, lanugo body hair, and peripheral edema.

The patient with bulimia nervosa must meet the criteria as outlined by the Diagnostic and Statistical Manual-Fifth Edition (DSM-V). These include eating large amounts of food within a short period, a lack of control over one’s eating, and recurrent compensatory behaviors to stop weight gains, such as laxative abuse, diuretic abuse, purging, or excessive exercise.  They tend to be excessively focused on their body weight.

Individuals with binge eating disorder are often overweight because of a higher than normal food intake.  They are not as obsessed with body weight but are concerned with getting enough food to eat. They tend to eat in secret and will hoard food. They will normally eat in front of others but binge alone.  They have physical findings associated with being overweight or obese, such as hypertension, high blood sugars, and hyperlipidemia.  Heart disease can be a secondary finding.

Etiology

The cause of anorexia nervosa is a complex interplay between biological, social, and psychological factors.  Women and adolescents are more prone to the disorder.  There is often the coexistence of an anxiety disorder.  These patients use their mastery over food and their weight to cope with anxiety, and feelings of having a lack of autonomy over their body and their life.  There is a modern focus on weight and expectations around weight that also play a role in getting the disorder.

The exact cause of bulimia isn’t known, but it is also believed to be some interplay between biological factors, psychological factors, and societal expectations around eating and weight.

The cause of binge eating disorder isn’t known for sure, but it may be a combination of biological factors (hormonal or genetic factors), psychological factors (such as depression and anxiety being comorbid states), and cultural factors (having a history of sexual abuse or other childhood trauma).  People who often receive critical comments about their weight may be at an increased risk of developing binge eating disorder.

Pathology

Eating disorders are diagnosed by clinical history, although bloodwork and an ECG might be necessary to see what the effects of that eating disorder might be on the body.  Basic tests that are often done in anorexia nervosa include a complete physical and mental status examination, metabolic panel, CBC, urinalysis, serum pregnancy test, and an ECG to look for cardiac electrical changes.  The same tests are done for bulimia nervosa and binge eating disorder. There are no imaging studies that can help identify the disorder.

Treatment and Management

The initial treatment of choice for anorexia nervosa is refeeding the patient. This must be an extremely slow process so that refeeding syndrome is avoided.  Refeeding syndrome involves starvation-related hypokalemia and hypophosphatemia, and cardiovascular collapse from feeding too fast after starvation.  Electrolyte replacement is also a big factor in the initial treatment steps.

Most patients need some psychiatric or psychological therapy, such as cognitive behavioral therapy, insight-oriented therapy, interpersonal therapy, cognitive analytic therapy, and family-based therapy. The use of medications is optional and mainly include SSRI therapy, such as fluoxetine, or the use of low doses of olanzapine for ruminating thoughts.

Patients with bulimia nervosa can be treated with cognitive behavioral therapy, interpersonal psychotherapy, or family therapy.  Pharmacological agents used to treat bulimia include fluoxetine (which is FDA-approved for the disorder) and other antidepressants, many of which can resolve the symptoms if used along with psychotherapy. Mood stabilizers have adverse side effects but have been found to be helpful in treating this disorder.

People with binge eating disorder will respond to a variety of psychotherapeutic techniques, including cognitive behavioral therapy, dialectical behavior therapy (DBT), or interpersonal psychotherapy (IPT). Eating disorder support groups are also helpful. Patients who have undercurrent depression or anxiety can be treated with psychotropic medications that help these problems.

Complications

The eating disorder with the greatest complication rate is anorexia nervosa.  About ten percent of patients will die from starvation.  Half will make a complete recovery, while the other half will remain very thin or emaciated.  Death from suicide is another complication of both anorexia nervosa and bulimia nervosa.

The biggest complications from binge eating disorder come from being obese or overweight. Some of the more typical complications include hypertension, heart disease, stroke, hyperlipidemia, and type 2 diabetes. These patients also have comorbid psychiatric disorders, and are at a greater risk for suicide attempts and completed suicide.

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