Choice architectural nudge interventions to promote vegetable consumption based on automatic processes decision-making

Objective: To test the effectiveness of three types of choice architectural nudges to promote vegetable consumption among Danish people. The experiment aims at providing evidence on the influence of automatic processing system in the food choice situation in an all you can eat buffet serving. Methodology: Experimental cross-over design study in the FoodScape Lab, comparing control to exposure of three nudges: Nudge 1: Natural green - priming vegetable-choosing behaviour. Nudge 2: Having a pre-weighed (200g) fixed salad as default to the main course, and Nudge 3: presenting each component of the salad separately to increase choices compared to a pre-mixed salad. Results: A total of 92 people (dropout rate=21 %) partook in the study (60.2% female) with an average age of 26.5. Nudge 1 (N=27) found a significant decrease in total energy consumption due to high decrease in meat consumption (p<0.001) but no significant change in vegetable in- take (p=0.16). Nudge 2 (N=33) found a significant increase in vegetable consumption (p=0.018) while Nudge 3 (N=32) found no impact on vegetable intake (p=0.56) but a decrease in total energy intake due to a decrease in meat intake (p<0.001 ). Key Findings: Only the Nudge that had a default portion size of vegetable had he intended impact of increasing vegetable consumption. This emphasises the importance of portion sizes in out of home eating as well as underlines the effect of the one-unit bias. The remaining two nudges were not successful in increasing vegetable intake, but promoted health by decreasing total energy intake which suggests that visual variety of fruit and greens prompts a healthy-eater subconscious behaviour.