Weight status is associated with clinical characteristics among individuals with bulimia nervosa

Recent studies have found increasing rates of overweight and obesity in bulimia nervosa (BN). However, the relationships between body mass index (BMI) and BN symptoms and other clinically relevant constructs are unknown. Participants (N = 152 adults with BN) were assigned to three groups by BMI: group with no overweight or obesity (NOW-BN; BMI <25; N = 32), group with overweight (OW-BN; BMI ≥25 and <30; N = 66), and group with obesity (O-BN; BMI ≥30; N = 54). We compared the groups on demographics, diet and weight histories, body esteem, BN symptoms, and depression using chi square, analysis of variance, analysis of covariance, and Poisson regression models. The O-BN group was older (d = 0.57) and OW-BN and O-BN groups had greater proportions of race/ethnic minorities than NOW-BN group. The O-BN group was significantly younger at first diet (d = 0.41) and demonstrated significantly higher cognitive dietary restraint (d = 0.31). Compared to NOW-BN, O-BN participants had lower incidence of objective binge eating (incidence rate ratio [IRR] = 4.86) and driven exercise (IRR = 7.13), and greater incidence of vomiting (IRR = 9.30), laxative misuse (IRR = 4.01), and diuretic misuse (d = 2.08). O-BN participants also experienced higher shape (d = 0.41) and weight (d = 0.42) concerns than NOW-BN and OW-BN, although NOW-BN experienced higher shape (d = 0.44) and weight (d = 0.39) concerns than OW-BN. Groups did not differ on depression scores. These results were replicated when examining BMI as a continuous predictor across the full sample, with the exception of objective binge eating and driven exercise, which were not significantly associated with BMI. Individuals with BN and comorbid obesity have distinct clinical characteristics. Existing interventions may need to be adapted to meet clinical needs of these individuals.