The role of premorbid body mass in binge eating and related symptoms

Given the potential detrimental consequences of eating disorders, it is important to understand the causal and maintaining factors in binge eating and associated symptoms, such as compensatory behaviors and depression. There is some evidence that individuals who exhibit bulimic symptoms tend to have elevated premorbid weights, and that having a greater discrepancy between a past high weight and current weight is indicative of a more severe disorder. These findings may reflect a predisposition among eating disordered individuals toward higher-than-average weights or a biological or behavioral drive to regain lost weight. A previous high weight may also independently exert negative psychological effects much later due to the concern it gives an individual about returning to that weight. However, current models of bulimia underemphasize the role weight plays in initiating and maintaining symptoms. The current study therefore aims to clarify the role of premorbid weights in current bulimic-cluster symptoms by examining pediatric growth charts of patients admitted to a residential treatment center for eating disorders. We found that our entire sample, which included those with and without binge eating, exhibited BMI z scores that were higher than the population mean at some point before developing an eating disorder. Among those who exhibited bulimic symptoms, we also found that highest premorbid BMI z score did not predict binge eating, purging, or compensatory behaviors, contrary to hypotheses. However, highest premorbid BMI z score predicted current depression, although the finding was no longer significant after controlling for current BMI and weight suppression. The lack of significant findings may suggest that premorbid weight does not confer risk for later bulimic-cluster symptoms. Conversely, our medium-to-large effect sizes suggest that absence of significant findings could be due to inadequate sample sizes. Therefore, the role of premorbid weight in bulimic and related symptoms warrants further research.