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

Introduction: The Mediterranean diet is being studied as an alternative to surgery for common gastrointestinal conditions. However, dietary change can be challenging. "Nudges" - behavioral science strategies seeking to influence cognitive processes to promote good behaviors - may help. We conducted a pilot study evaluating the acceptability of the MediDiet, a behaviorally designed dietary intervention incorporating nudges and recommendations based on the Mediterranean Diet. Methods: We conducted a three-phase pilot study involving parallel randomized surveys of U.S. adults. After completing a validated questionnaire assessing dietary consistency with a Mediterranean diet, participants were randomized to feedback containing no nudge versus nudge: peer comparison; peer comparison + positive affect induction; or default. Participants then rated their positive and negative emotions, motivation for dietary change, and interest in recipes. Responses were analyzed using baseline covariate-adjusted regression. Results: Among 1,709 participants, 56% were men, 73% were White, and the mean age was 38. In response to dietary feedback, participants reported low negative emotions, high positive emotions, moderate motivation for dietary change and high interest in recipes. Nudges did not affect the extent of negative (p=0.104) or positive (p=0.34) emotions, motivation (p=0.139), or interest (p=0.86). In exploratory analyses, those with moderate and high consistency with the Mediterranean diet, with or without nudges, reported lower negative affect, greater positive affect, greater motivation, and greater interest in recipes, than the minimally consistent, no nudge group. Conclusion: Delivering dietary feedback based on the Mediterranean diet using behavioral nudges was acceptable among U.S. adults, rousing positive reactions without triggering negative ones. As early evidence, this pilot study provides the basis for testing nudge-based dietary guidance among individuals with symptomatic gallstones, diverticulitis, and other gastrointestinal diseases.