Reciprocal association between session-by-session change in overvaluation of shape and weight and session-by-session change in bulimia nervosa symptoms during cognitive behavior therapies

ABSTRACT

Overvaluation of shape and weight (OSW) is supported as an important mechanism underlying improvement in bulimia nervosa (BN) during behavioral therapies (CBTs). It is not yet clear, however, whether changes in OSW temporally precede and prospectively predict changes in BN symptoms during CBTs, limiting the ability to establish causality. The present study is the first to examine whether session-by-session changes in OSW prospectively predict session-by-session changes in BN symptoms during CBTs and clinical outcomes at the end-of-treatment. Participants with BN (n = 44) who received 20 sessions of CBTs completed a brief survey at each session assessing OSW and BN symptom frequency during the past week. Results showed small but significant session-by-session reductions in OSW and BN symptoms during CBTs. Session-by-session improvements in OSW in any given week prospectively predicted reductions in restrictive eating, binge eating, and compulsive exercise in the following week but did not prospectively predict improvements in purging, while improvements in restrictive eating and compulsive exercise in any given week prospectively predicted reductions in OSW in the following week. Average session-by-session change in OSW during treatment was positively associated with remission status and improvements in eating pathology at the end-of-treatment. Changes in OSW temporally precede and prospectively predict changes in BN symptoms during CBTs, and vice versa. These findings may have critical implications for treatment planning and implementation.

Disclosure statement

No potential conflict of interest was reported by the authors.

Clinical significance

1. Overvaluation of shape/weight (OSW) is an established maintenance factor for bulimia nervosa (BN) and an important target of behavioral therapies (BTs).

2. The present study showed that OSW increased in the early phase of BTs before steadily decreasing in the later phases of treatment.

3. Session-by-session changes in OSW during BTs temporally precede and prospectively predict session-by-session changes in restrictive eating, binge eating, and compulsive exercise during treatment.

4. Session-by-session changes in restrictive eating and compulsive exercise temporally precede and prospectively predict session-by-session changes in OSW.

5. Overall, session-by-session change in OSW during treatment was positively associated with remission status and improvements in eating pathology at the end of treatment.

6. Our study suggests that changes in OSW may be an important mechanism underlying improvements in BN from BTs.

7. If replicated, our results indicate that clinicians may consider assessing for and addressing worsening of OSW during early phases of BTs for BN.

Additional information

Funding

This work was supported by the National Institute of Mental Health [K23MH105680].