According to Pamela Keel, associate professor of psychology in the UI College of Liberal Arts and Sciences, the disorder is similar to bulimia nervosa as both syndromes involve eating, then trying to compensate for the calories.
However, she says that what sets the disorders apart is the amount of food consumed and the way people compensate for what they eat. Women with purging disorder eat normal or even small amounts of food and then purge, often by vomiting. Women with bulimia have large, unrestrained binge eating episodes followed by purging, fasting or excessive exercise.
"Purging disorder is new in the sense that it has not been officially recognized as a unique condition in the classification of eating disorders. But it's not a new problem. Women were struggling with purging disorder long before we began studying it," Keel said.
Keel further says her study indicates that purging disorder is a significant problem in women that is distinct from bulimia.
For the study, Keel recruited participants for three groups: women without eating disorders; women who purge to compensate for binge episodes; and women with purging disorder who purge to control their weight or shape but do not have binge episodes.
The women completed self-report questionnaires and clinical interviews. They also had blood drawn before and after consuming a liquid test meal and reported their feelings throughout the meal, including feelings of fullness, hunger, sadness or tension.
After thorough examination, Keel discovered that women with purging disorder tend to share some characteristics with bulimics: Both experience greater depression, anxiety, dieting and body image disturbance than women without eating disorders.
But the study also provided evidence that purging disorder is a distinct illness. Women with purging disorder differed from women with bulimia on a physiological mechanism that influences food intake. Those with purging disorder also reported greater fullness and stomach discomfort after eating compared to women with bulimia and women without eating disorders.
Keel said more research on purging disorder is needed to better understand the condition and to support its inclusion in the classification of eating disorders.
"Because we tend to only study formally defined disorders, this creates a gap between the problems people have and what we know about those problems. Identifying this disorder would stimulate research on its causes, treatment and prevention, which could alleviate the distress and impairment women with the illness suffer," she said.
Keel is now seeking participants for a follow-up study. Normal-weight women ages 18 to 45 who binge and purge, fast or exercise, or who only purge, may be eligible to participate in the study. The format of the follow-up study will be similar to the previous study.
The study is published in the Archives of General Psychiatry.