Premorbid BMI predicts binge-purge symptomatology among individuals with anorexia nervosa

A finding consistent with the transdiagnostic approach to eating disorders is that about half of those with restricting anorexia nervosa (AN) eventually undergo a transition to the binge/purge (BP) subtype or to bulimia nervosa. Given evidence that individuals with bulimic symptoms exhibit elevated weights premorbidly, we tested the hypothesis that among those with AN, highest premorbid BMI would predict which individuals with AN would develop AN-BP.

The current study used longitudinal data from a community sample of adolescents with AN in Sweden. Premorbid weights were obtained from growth charts, and participants were re-assessed at 6, 10, and 18 years after first presentation with AN.

A greater highest premorbid BMI z score predicted a greater likelihood of developing binge/purge symptoms over 18 years.

Among individuals who develop an eating disorder, premorbid BMI may be implicated in the type and course of the eating disorder that emerges.