Nudging food service users to choose fruit- and vegetable-rich items: Five field studies.

Although nudging has been found to promote the choice of healthy foods in lab studies and ad-hoc field studies, relatively little research is available regarding effectiveness in real food venues that operate for profit. The paucity of empirical studies providing "proof of implementation" reveals the difficulty of applying previous empirical findings on nudging to mass-eating food services contexts, which serve meals to a lot of individuals daily. Based on the typology of choice architecture in food choice contexts, we closely collaborated with the in-house food service operator to devise and implement five nudge interventions to promote fruits and vegetables (FV) in university cafeterias. Each study was conducted for one 12-week semester or more over a three-year period. In the first two studies, non-verbal point-of-purchase prompting increased the choice of kale/spinach supplemented smoothies and whole fruits from baskets. In Study 3, the combination of sizing and point-of-purchase non-verbal prompting increased the sale of large size vegetable-rich bowls from a stir-fry grill. In Study 4, the proximity type of nudging by altering the position of the healthier option in a sandwich bar in combination with non-verbal prompting increased the sale of sandwiches containing spinach. In Study 5, the combination of sizing and proximity of large vs. small sized plates and serving spoons had no effect on sale of self-serve items in a salad bar. All the interventions except for Study 5 produced a moderate effect in increasing the choice of FV-rich items. We recommend that hospitality and food service operators consider operational parameters and simultaneously adopt more than one nudging components to achieve a sizable effect. Future randomized controlled trials are needed to implement choice architecture techniques in collaboration with food service companies.