Effects of implementation intentions and mental imagery on subjective binge eating.

Objective: Binge-eating disorder (BED) and bulimia nervosa (BN) are characterised by binge eating. Changing unwanted behaviour is difficult, as intentions do not automatically lead to action. Implementation intentions (IIs) may help bridging the gap between intentions and behaviour. IIs are 'if-then' plans promoting goal attainment. Effects are moderated by degree of plan formation. Using mental imagery (MI) to impress IIs may strengthen plan formation and goal attainment.

Method: In a students' sample with subjective binge eating, we compared IIs without MI, IIs with MI, and a control condition regarding their ability to reduce binge eating. Participants received three II-sessions and kept food diaries for 4 weeks.

Results: Results showed a significant and medium to large reduction of binge eating in both II-conditions compared to the control condition, that was sustained for 6 months. No additional effects of MI were found.

Conclusions: Applying IIs results in long-lasting reductions in subjective binge eating. The absence of additional effects of MI may be due to floor effects. Also, participants in the IIs without MI condition may have applied MI without being instructed to do so. In future research, ideally with a clinical sample, it is recommended to prevent or control for this.