Update on Eating Disorders: Anorexia, Bulimia, and Binge Eating

The eating disorders anorexia nervosa, bulimia nervosa, and binge eating disorder (BED) may affect up to 24 million Americans. Although these disorders are much more common in women, men account for up to 15% of people with an eating disorder.1

“Binge eating disorder is the most common eating disorder, followed by bulimia and anorexia,” says Marsha Marcus, PhD, a professor of psychiatry and psychology at the University of Pittsburgh School of Medicine and chief of the eating disorders program at the Western Psychiatric Institute and Clinic, University of Pittsburgh Medical Center.2

BED is recurrent episodes of overeating in short periods of time. The condition differs from common overeating in that there is significantly greater amount of food eaten, feelings of guilt, and lack of control. The disorder is also characterized by significant physical and psychological harm. Bulimia nervosa is similar to BED, but also includes inappropriate purging, such as self-induced vomiting to avoid weight gain.2,3

Anorexia is the most dangerous eating disorder with the highest mortality rate of any psychiatric disorder.4 Anorexia causes a distorted body image, excessive dieting, a pathologic fear of becoming fat, and severe weight loss.2 This results in a cycle of self-starvation that may be fatal in up to 15% of cases.5

“What links all the eating disorders is a persistent alteration in the consumption and absorption of food,” says Marcus. “All these disorders have multiple causes that include genetics, neurobiological changes, and cultural influences. Neurocircuits for value, response, and reward around food become abnormal. In anorexia, this results in undereating. In bulimia and binge eating, this results in overeating. As far as an exact cause, no one knows.”

Eating Disorder Changes in DSM-5

In 2013, changes were made in the DSM-5 in regards to eating disorders.

“The changes are not radical but are meant to improve clinical utility,” says Robyn Sysko, PhD, assistant professor of psychiatry at the Icahn School of Medicine at Mount Sinai in New York City, and member of the DSM-5 eating disorders working group along with Marcus.

“The biggest change was creating a new diagnostic category for binge eating disorder,” says Sysko.

In DSM-IV, BED was recognized as an eating disorder not otherwise specified that needed further study.  “We now have enough studies to show that binge eating disorder is a distinct disorder with its own course and outcome. The criteria were changed slightly for the frequency threshold, from twice per week to once per week. This change also applies to bulimia,” Sysko explains.

DSM-5 also made some changes to anorexia. Amenorrhea — the absence of menstruation — had been part of the criteria in DSM-IV, but that has been dropped. “Amenorrhea was dropped because some men have anorexia, and some women continue to have menstrual cycles even with severe anorexia,” says Marcus.

“We also changed wording in the description. We eliminated using a percentage of body weight to describe weight loss and replaced percentage with the term ‘significant weight loss.’ The term ‘refusal’ of adequate calorie intake was removed. Refusal was thought to be too pejorative. We replaced refusal with avoidance,” Sysko adds.

Treatment of Eating Disorders

Treating an eating disorder is challenging. “Psychotherapy for bulimia and binge eating disorder is adequate treatment for 30 to 50% of patients,” says Marcus. “Psychotherapy has not been shown to be as helpful for anorexia. The only FDA-approved medication is fluoxetine (Prozac) for bulimia. These disorders also have a very high rate of comorbidities, all of which makes treatment difficult.

Substance abuse, mood disorders, and obsessive-compulsive disorder are common with all eating disorders. Obesity is a common complication of BED.

Cognitive behavioral therapy (CBT) is the treatment of choice for bulimia and is more effective than medication alone,” says Angela Guarda, MD, an associate professor of psychiatry and director of the Johns Hopkins Eating Disorders Program in Baltimore.

“Around 50% of patients with bulimia respond to a 20-week course of CBT. Importantly, self-help approaches are also effective for a substantial proportion of patients and are more accessible and cost-effective than specialty care. The medication with the best support in bulimia is high-dose fluoxetine.”

As with bulimia, the best evidence supports CBT as the first-line intervention for binge eating disorder. Again as in bulimia, high-dose fluoxetine is the most established agent with efficacy, and high doses work better here too,” Guarda adds.

Finding other drugs to treat BED has been an active area of research, although the studies have been small and limited by a high placebo response and dropout rates. Antidepressants have been shown to be moderately effective. Several double-blind, placebo-controlled studies have found that the anticonvulsant topiramate is effective for treating BED and obesity associated with BED. Other drugs that have been tried include stimulants and medications used to treat substance abuse.6