Applying Behavioral Nudges in a Dietary Comparator for Surgical Trials: Developing the MediDiet.

Introduction: Dietary interventions are increasingly being proposed as alternatives to surgery for common gastrointestinal conditions. Integrating aspects of cognitive psychology (e.g., behavioral nudges) into dietary interventions is becoming popular, but evidence is lacking on their effectiveness and unintended effects. We assessed the effects of including nudges in the development of a dietary intervention based on the Mediterranean diet.

Methods: We conducted two-arm randomized surveys of United States adults. After a validated dietary questionnaire, participants received feedback about dietary consistency with a Mediterranean diet with (A) no nudge versus (B) one of several nudges: peer comparison, positive affect induction + peer comparison, or defaults. Participants rated their negative and positive emotions, motivation for dietary change, and interest in recipes. Responses were analyzed using baseline covariate-adjusted regression.

Results: Among 1709 participants, 56% were men and the median age was 36 y. Nudges as a class did not significantly affect the extent of negative or positive emotions, motivation, or interest. However, specific nudges had different effects: compared to no nudge, peer comparison blunted negative emotions and increased motivation, although decreased interest in recipes, while defaults increased interest in recipes but reduced motivation.

Conclusions: In this pilot, behavioral nudges as a class of strategies did not improve participants' reactions to dietary feedback nor did they promote negative reactions. However, specific nudges may be better considered separately in their effects. Future testing should explore whether specific nudges including peer comparison and defaults improve dietary intervention effectiveness, especially in people with the specific gastrointestinal conditions of interest.