A University of Iowa professor is making a case for a new eating disorder she calls purging disorder.
The disorder is similar to bulimia nervosa in that both syndromes involve eating, then trying to compensate for the calories. 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, out-of-control 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," said Pamela Keel, associate professor of psychology in the UI College of Liberal Arts and Sciences, "But it's not a new problem. Women were struggling with purging disorder long before we began studying it."
In a paper published in the Archives of General Psychiatry, Keel shares the results of a study indicating that purging disorder is a significant problem in women that is distinct from bulimia.
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. Participants came from the Boston and Iowa City/Cedar Rapids areas and were within a healthy weight range. 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.
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," Keel said. "Identifying this disorder would stimulate research on its causes, treatment and prevention, which could alleviate the distress and impairment women with the illness suffer."
UI researchers are 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.
Keel hopes to find out why some women feel the need to purge after eating what most people would regard as a normal or even small amount of food. She hopes this information will provide insight into what types of treatments may be effective for purging disorder.
"Right now there are no evidence-based treatments for purging disorder," Keel said. "It would be a disservice to women with purging disorder to assume that treatments that work for bulimia nervosa will work for purging disorder, given the differences we found between the syndromes. Additional research is crucial for advancing our understanding of purging disorder."
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