The dramatic rise in obesity over the last decade has heightened debate among psychiatrists about whether “binge eating disorder” is a distinct clinical entity that deserves to move from the appendix of the DSM-IV up to a full-fledged psychiatric diagnosis in the DSM-V.
Since the DSM-IV was published in 1994, the prevalence of obesity among adults in the United States has risen by at least 30%. One-third of the U.S. population is currently considered obese, with a body mass index of 30 kg/m2 or greater, and more than two-thirds are overweight, with BMIs at or above 25.
Largely hidden in these statistics are roughly 2% of the population who meet the proposed binge eating disorder (BED) criteria (See box)–and who make up about one-third of individuals who seek help in weight loss treatment programs–as well as the unknown but undoubtedly huge number of people who don't meet the BED criteria but exhibit abnormal eating behavior linked to negative emotional states.
“There's a lot of interest in this topic, much of it related to how the fields of behavioral medicine and psychiatry can make a contribution to both the understanding and treatment of obesity,” said B. Timothy Walsh, M.D., who chaired the DSM-IV committee on eating disorders.
The term “binge eating disorder” is widely used in research and clinical settings, but BED is not an official diagnostic category. It is included in the DSM-IV under “criteria sets and axes for further study.” Patients who now meet the definition are classified either by other comorbid conditions such as depression or anxiety, and/or under the heading of “eating disorders not otherwise specified” (EDNOS).
The EDNOS category has proved problematic, because it lumps BED in the same category with a young woman who meets all the criteria for anorexia nervosa except that she still menstruates. It also refers to the patient who binges and purges but not quite often enough to qualify for bulimia nervosa. “There's been a lot of discussion about how to handle the EDNOS issue. It's a heterogeneous mix,” noted Dr. Walsh, director of the eating disorders research unit at New York State Psychiatric Institute/Columbia University, New York.
And BED patients are demographically very different from those with either anorexia or bulimia. They tend to be middle-aged at the time of diagnosis as opposed to an adolescent or young adult, and are as likely to be black or Hispanic as white, while patients with the other common eating disorders are primarily white. And, although BED is seen more often in women than in men, the ratio is about 60/40, compared with the 90/10 female/male ratio seen with anorexia and bulimia.
So, although BED is a distinct entity–these patients eat more in a shorter period of time than do other obese individuals–the primary reason that it didn't make it into DSM-IV is that “there are not compelling data that people who meet the criteria have a different need for treatment and/or a different prognosis than people who could be described equally well by existing categories. That evidence is still lacking,” Dr. Walsh said.
“The fact that most people with BED are obese, and most have some symptoms of anxiety or depression makes one wonder if those labels aren't sufficient. I don't think we should be casual about applying labels. We have to be rigorous in our insistence that the evidence backs up the utility of labels, because once they get created and formally approved, it's very hard to erase them,” he remarked.
Carlos M. Grilo, Ph.D., professor of psychiatry and director of the eating disorders program at Yale University, New Haven, Conn., agrees. “There is still active debate about the BED term. There is a clinical reality: Patients do suffer from problems described by the term. The research shows that persons who binge eat have increased psychiatric problems and psychological distress. But, do they benefit less from obesity treatment programs than do obese individuals who don't binge eat? That's not clear.”
Indeed, the only clear conclusion about BED treatment is that both cognitive-behavioral therapy (CBT) and interpersonal therapy (IPT) effectively reduce binge eating behavior. Both seem to work equally well, although more data are available for CBT. In one randomized comparison of CBT and IPT conducted in group settings for 20 weeks, binge eating recovery rates were equivalent among 81 patients in each group: 64 (79%) with CBT, compared with 59 (73%) with IPT post treatment. At 1 year follow-up, 59% who received CBT and 62% with IPT were still in remission (Arch. Gen. Psychiatry 2002;59:713–21).