For much of the 30 years that bulimia has been recognized as a psychiatric disorder, experts have believed that unlike anorexia, bulimia was purely a psychological issue, and not also a physiological one. Bulimics were thought to be generally normal weight people who have an extreme phobia about weight gain.
But recent research, published this month in the International Journal of Eating Disorders, has cast doubt on that assumption, and could serve as a motivational tool for bulimics struggling to recover. A study out of Drexel University in Philadelphia found that among two different sets of people studied, one over a period of 20 years and the other for two years, one surprisingly accurate indicator of how patients with bulimia will fare is the discrepancy between their past all-time high weight and their current weight. The larger that discrepancy, known as “weight suppression,” is, the more likely patients are to gain weight while their bulimia continues.
Study lead author Jena Shaw, M.S., a graduate student of clinical psychology at Drexel, says that for about 60 percent of those studied, “at some point their bulimic behaviors start to backfire on them.”The weight gains she and her colleagues measured were “about forty pounds in three years, an average of about fifteen pounds a year.” Although the reasons for such weight gains are still unclear, one possibility is that bulimia patients tend to be higher weight than their peers, which leads them to begin dieting. When weight reaches borderline or underweight levels, we know from studies on starvation that bingeing is a likely response. Phobic about the large number of calories consumed, the patient begins to purge, setting off a vicious binge-purge cycle.
“If most of them are weight suppressed, well below the highest weight they’ve been, their symptoms and susceptibility to weight gain are due at least in part to the weight suppression, not just to their mental state," explains another researcher involved in the study, Dr. Michael Lowe, professor of psychology at Drexel and research consultant to the Renfrew Center.
Shaw hopes that based on these findings, physicians treating patients with bulimia will make it standard practice to weigh bulimia patients when they first enter treatment and ask for their previous highest weight.
Warning patients who are high in weight suppression that if they continue bingeing and purging they are likely to gain weight, possibly to a level greater than their previous highest weight, could help motivate them to learn healthier ways of controlling their eating and weight.“Weight gains [among those patients studied] tend to be so dramatic that they have a better chance if they learn healthy weight control skills,” Shaw explains. The goal is to stop bingeing and purging in order to prevent the future weight gain that their past history seems to predict.
To put this study in perspective, Dr. Lowe says, “it really takes on more significance when added to approximately ten or twelve studies on weight suppression in bulimia that have been done…it makes a lot more sense realizing that it fits into a larger literature.”