Researchers at Drexel University have found that a majority of women with bulimia nervosa reach their highest-ever body weight after developing their eating disorder, despite the fact that the development of the illness is characterised by significant weight loss.
Their new study, published online in the International Journal of Eating Disorders, adds to a body of recent work that casts new light on the importance of weight history in understanding and treating bulimia.
"Most patients lose a lot of weight as part of developing this disorder, and all dedicate significant effort, including the use of extreme behaviours, to prevent weight gain," said Jena Shaw, a clinical psychology doctoral student in Drexel's College of Arts and Sciences who was lead author of the new study. "In spite of this, we found that most women also regain a lot of weight while they have bulimia. We want to find out why that is."
Working with Dr Michael Lowe, a professor of psychology at Drexel, and other collaborators, Shaw examined data from two study populations of women with bulimia, including a group of 78 women who were patients at the Renfrew Center in Philadelphia studied over two years, and a group of 110 women from a Harvard study who were interviewed at six-month intervals for eight years.
"Most of the women we studied reached their highest weight ever after developing bulimia and before remission," Shaw said. A total of 59% of women in the two-year study population, and 71.6%of women in the eight-year study population, showed this weight history pattern. These weights were even higher than their weights before developing bulimia, despite the fact that their pre-bulimia weights were overall already higher than average.
The researchers also explored group differences between women who reached their highest weight after onset of bulimia, and those whose highest weight preceded the eating disorder. The women who reached a new highest weight during bulimia had generally developed the disorder at an earlier age, and struggled with it for a longer period of time.
The importance of weight history
These findings add to a body of work led by Lowe that emphasises the importance of weight and weight history in the outcomes and treatment of bulimia. Lowe's research has quantified relationships between personal weight history and the symptoms and outcomes of eating disorders.
"Bulimia nervosa was first medically described in 1979 among patients whose body weight generally appeared 'normal,' but who, in most cases, had weighed substantially more in the past," said Lowe. "Yet relatively few studies have considered weight history or the fear of becoming overweight again as a possible perpetuating factor for the disorder."
In his eating disorder studies, Lowe has examined a variable called "weight suppression," which is the difference between a person's past highest weight and her current weight. Most people with bulimia have higher weight suppression values than their peers without bulimia. His studies have shown correlations between higher weight suppression in bulimic women and undesired outcomes including greater likelihood of dropping out of treatment, less likelihood of abstaining from binge/purge behaviours, greater weight gain and longer time to remission.
Recently, other researchers have found a relationship between weight suppression and metabolism in healthy women, suggesting that people with higher weight suppression must eat fewer kilojoules to maintain their weight than women of similar weight who have always been close to their current weight.
By clarifying the connections between women's weight history and the course of their eating disorder, researchers may identify ways to use productive discussion of weight and weight history to improve treatments, Lowe said.
(EurekAlert, February 2012)