Abstract Bulimic individuals typically lose a substantial amount of weight in the process of developing their disorder. Such weight suppression (WS) may be behaviorally and metabolically problematic. The present study tested the hypothesis that WS would predict weight gain during the inpatient hospitalization of 146 bulimia nervosa-spectrum inpatients. WS represented the difference ( M = 12.0 kg) between highest weight ever and current body weight. Controlling for length of stay and current dieting (EAT-D scores), high levels of WS predicted greater weight gain. Furthermore, WS and admission BMI independently predicted weight gain when entered together in a regression analysis. Weight gain was also related to clinical improvement. These findings suggest that weight suppression, independently of current dieting status, may produce psychobiological pressures toward weight gain and could complicate the treatment of bulimia nervosa.