Washington: A new research has tried to look into the principle as to why the more weight you lose, the harder it is to keep it off.
The study claims that a complex and vicious cycle of biological and behavioral factors make it so.
But eating disorder research has largely overlooked this influence, and Dr. Michael Lowe, a professor of psychology at Drexel University, has published a flurry of research studies showing that needs to change.
"The focus of eating disorder research has very much been on the state of patients' thoughts, beliefs, emotions and personalities," Lowe said.
"And while these mental influences are undoubtedly part of the problem, historically there has been very little focus on how their current and past body weights contribute to their eating disorder," he said.
Lowe and colleagues' studies - about a dozen on bulimia nervosa have been published in the past several years - show that having an elevated past body weight, and being at a body weight well below highest past weight, may help cause and perpetuate disordered eating.
The latest of Lowe's studies is the team's first to address this principle in anorexia nervosa.
The findings, Lowe says, show that researchers and clinicians need to start taking into account how a person's historical and current body weight contribute to disordered eating.
"This fundamentally changes the assumption that the problem is primarily psychological or emotional," Lowe said.
The new study, led by doctoral student Laura A. Berner, was based on data collected at the Renfrew Center for eating disorders in Philadelphia, where Lowe is also a consultant.
The researchers found that the level of eating disorder symptoms, as well as degree of improvement during treatment, depends on how much weight patients with anorexia nervosa had lost from their previous highest weight (a measure called " weight suppression"), how much they currently weigh and the interaction between the two.
The study is published in The Journal of Abnormal Psychology, the top journal for eating disorder research.