Nudges for more sustainable food choices in the out-of-home catering sector applied in real-world labs

Food production is responsible for approximately 17% of Germany's greenhouse gas (GHG) emissions. After retail, out-of-home catering is the second largest food sales channel in Germany. A variety of means on both the supply and demand side are necessary to stimulate, facilitate and encourage a more sustainable development and minimise GHG emissions in this sector. Nudges are one of these. This paper's focus lies on the demand side. Set in real-world laboratories, we use a standardised empirical approach to compare different nudging interventions belonging to the area of physical environment and consumers’ choice making process. We compare the effects of the same intervention across different settings and the effect of different, sequential nudging interventions in the same setting. Data was collected in eight workplace and school cafeterias in Germany over two project iterations (2016/2017; 2019/2020). A similar intervention design was applied. Comparability was assured by a harmonised menu. The first project iteration revealed that only one nudge (top menu position, +22.5%) led to significant increases in sustainable food choices, while results from the second iteration showed that all nudge interventions (best counter position, +11.6%; top menu position, +6,9%; label plus information, +15.9%) positively influenced consumer choice. Possible explanations such as the stricter compliance to the experimental design in the cafeterias but also societal developments such as the appearance of the Fridays for Future movement are discussed. As results vary between specific locations and settings, our findings suggest that nudges need to be adjusted to situational conditions for achieving highest efficacy