Recent studies suggest that weight suppression (WS), defined as the discrepancy between current and highest past weight, predicts short-term weight gain in bulimia nervosa (BN) during treatment. The current study was designed to build on this preliminary work by examining the relation between WS and long-term weight change in BN. Treatment-seeking women (N = 97) with DSM-IV BN participated in a naturalistic longitudinal follow-up study of eating disorders. At intake, height and weight were measured and highest past weight was assessed. Self-reported weights were collected every 6 months for 5 years. Hierarchical Linear Modeling (HLM) estimated growth curves for weight change over time. Significant inter-person variability was detected for intercepts and slopes (P < 0.001) so both were treated as random effects. Participants' weights increased over the study course, moderated by baseline WS (P < 0.001), such that higher WS predicted more rapid weight gain. Weight change was not associated with entry weight, height, or highest-ever weight, suggesting that WS per se predicted weight change. These findings complement previous short-term studies in BN by demonstrating that WS predicts weight gain over 5 years. Because weight gain could spur radical dieting that maintains BN, these results have important treatment implications.
Most individuals with bulimia nervosa (BN) are in the normal weight range, yet their apparently unremarkable body weight conceals a history of once weighing considerably more than they currently do. This discrepancy, which Lowe (1993) has labeled “weight suppression” (WS), was emphasized by Russell (1979) in his classic paper that first identified BN as an eating disorder, but has been little studied since. Weight suppression is defined as the difference between highest past weight (since reaching adult height) and current measured body weight. Individuals with BN are high in WS; Butryn et al. (2006) reported a mean WS of 9.6 kg in outpatients and Lowe et al. (2006) reported a mean WS of 12.0 kg in residential patients with BN. Because individuals in these studies had body mass indices (BMI; kg/m2) in the middle of the normal weight range, this means that many of those with BN were once overweight, an observation that coincides with the weight history findings from a community-based study of BN (Fairburn et al., 1997).
Interestingly, though much has been written about how weight loss in obese individuals may set the stage for weight regain (Rosenbaum et al., 2008), few such concerns have been raised about the major weight losses most individuals with BN have undergone. The weight losses experienced by individuals with BN may be of even greater concern because, given that most women with BN have never been obese, a weight loss of a given size represents a larger percentage reduction in most individuals with BN than in obese individuals. Furthermore, if reducing weight well below its highest previous level makes weight gain more likely, such effects could exacerbate bulimic behavior because the dieting that may be required to avoid or reverse weight gain could drive the maintenance of binge eating and purging (Fairburn et al., 1993b). Studies have in fact found that WS predicts weight gain in nonclinical women (Lowe et al., 2006), in outpatients with BN (Carter et al., 2008), and in residential patients with BN (Lowe et al., 2006). Lowe et al. (2007) found that WS was positively related to the frequency of objective binge eating in individuals with BN and Butryn et al. (2006) found that greater WS predicted poorer outcome (study dropout and continuation of eating disorder symptoms at the end of treatment) in the cognitive–behavioral treatment of BN (though Carter et al. (2008) did not replicate this effect). These studies suggest that individuals with BN who are high in WS may be caught in a “biobehavioral bind”: Suppressing their weight may reduce their feelings of fatness and unattractiveness but may fuel binge eating, purging and eventual weight gain, leading to renewed intensive dieting and further binge eating and compensatory behavior.
Although WS has been consistently predictive of weight gain from periods ranging from several weeks to several months, no study has examined its longer-term relation to weight change. If WS as a predictor of weight gain is restricted to small amounts of weight over relatively brief periods of time, then its role in the perpetuation of BN may be limited. However, if WS predicts large weight gains over long periods of time, then it may play a more significant role in the maintenance of BN because such weight gain would presumably be anathema to these individuals, leading to intensified weight loss efforts that help perpetuate the disorder.
The Massachusetts General Hospital (MGH) Longitudinal Study of Anorexia and Bulimia Nervosa is a prospective, naturalistic examination of 246 treatment-seeking women with anorexia nervosa (AN) or BN. The detailed longitudinal weekly data available from study participants offers a unique opportunity for investigating the relationship between WS among women with BN and prospective weight change. The availability of comprehensive assessment data at entry also allowed us to examine whether relevant covariates (i.e. age and entry BMI) might account for any prospective prediction of weight change by WS at entry. This study extends the design of previous studies by investigating weight change over a longer duration of follow-up and by assessing weight at frequent intervals. Based on the prediction of short-term weight gain in previous studies of WS, we hypothesized that weight suppression at study entry would predict greater weight gain over 5 years.
