Nudging towards sustainable dining: Exploring menu nudges to promote vegetarian meal choices in restaurants.

Food choice behavior plays a large role in achieving sustainability goals. Meat in particular has a negative environmental impact as compared with plant-based food - and is more frequently chosen in restaurant contexts. To increase plant-based meal choices in restaurants, we tested three nudges for menus that are likely to be implemented by restaurant owners: a hedonic label (e.g., artisanal vegetable burger), a chef's recommendation (specifying the vegetarian option as the chef's favorite), and a salience nudge (a box around the vegetarian option). In an online experiment, we showed participants (n = 513) in four conditions (no nudge, hedonic label, chef's recommendation, and salience nudge) five menus with four meal options each, one of which was vegetarian. We asked participants to choose a meal and subsequently to rate these meals on how tasty and indulgent they were (taste and indulgence attributions). We then revealed which nudge was used to the participants and asked how participants received it. Results show that the hedonic label and chef's recommendation nudge (but not the salience nudge) both increase vegetarian meal choices. The hedonic label increased participants' attributions of indulgence of the meal, but not of tastiness. This finding fits with restaurants' gastronomic, pleasure-seeking context and shapes future directions of labeling interventions, namely that indulgence attributions can be increased in vegetarian foods. Furthermore, the nudges were generally well accepted and participants' intention to return to the (virtual) restaurant was high. Finally, customers expected the hedonic label nudge to be more effective in promoting vegetarian food choices than the other two nudges, partially corresponding with our findings of actual effectiveness.

Real-world nudging, pricing, and mobile physical activity coaching was insufficient to improve lifestyle behaviours and cardiometabolic health: the Supreme Nudge parallel cluster-randomised controlled supermarket trial.

BACKGROUND: Context-specific interventions may contribute to sustained behaviour change and improved health outcomes. We evaluated the real-world effects of supermarket nudging and pricing strategies and mobile physical activity coaching on diet quality, food-purchasing behaviour, walking behaviour, and cardiometabolic risk markers. METHODS: This parallel cluster-randomised controlled trial included supermarkets in socially disadvantaged neighbourhoods across the Netherlands with regular shoppers aged 30-80 years. Supermarkets were randomised to receive co-created nudging and pricing strategies promoting healthier purchasing (N = 6) or not (N = 6). Nudges targeted 9% of supermarket products and pricing strategies 3%. Subsequently, participants were individually randomised to a control (step counter app) or intervention arm (step counter and mobile coaching app) to promote walking. The primary outcome was the average change in diet quality (low (0) to high (150)) over all follow-up time points measured with a validated 40-item food frequency questionnaire at baseline and 3, 6, and 12 months. Secondary outcomes included healthier food purchasing (loyalty card-derived), daily step count (step counter app), cardiometabolic risk markers (lipid profile and HbA1c via finger prick, and waist circumference via measuring tape), and supermarket customer satisfaction (questionnaire-based: very unsatisfied (1) to very satisfied (7)), evaluated using linear mixed-models. Healthy supermarket sales (an exploratory outcome) were analysed via controlled interrupted time series analyses. RESULTS: Of 361 participants (162 intervention, 199 control), 73% were female, the average age was 58 (SD 11) years, and 42% were highly educated. Compared to the control arm, the intervention arm showed no statistically significant average changes over time in diet quality (ߠ- 1.1 (95% CI - 3.8 to 1.7)), percentage healthy purchasing (ß 0.7 ( - 2.7 to 4.0)), step count (ߠ- 124.0 (- 723.1 to 475.1), or any of the cardiometabolic risk markers. Participants in the intervention arm scored 0.3 points (0.1 to 0.5) higher on customer satisfaction on average over time. Supermarket-level sales were unaffected (ß - 0.0 (- 0.0 to 0.0)). CONCLUSIONS: Co-created nudging and pricing strategies that predominantly targeted healthy products via nudges were unable to increase healthier food purchases and intake nor improve cardiometabolic health. The mobile coaching intervention did not affect step count. Governmental policy measures are needed to ensure more impactful supermarket modifications that promote healthier purchases. TRIAL REGISTRATION: Dutch Trial Register ID NL7064, 30 May 2018, https://www.onderzoekmetmensen.nl/en/trial/20990.