How to use nudging to reduce food waste

In recent years, there has been increasing interest in using behavioral economics principles to "nudge" individuals towards making healthier and more sustainable choices. One area where these nudges may be particularly effective is in reducing food waste and increasing vegetable intake.

Nudging Greater Vegetable Intake and Less Food Waste

A new study by Qi et al. (2022) conducted a field experiment in a school cafeteria in the United States. They implemented three different nudging strategies aimed at increasing the vegetable intake among students and reducing the amount of food that was wasted: (1) offering smaller portion sizes, to encourage students to take only what they can eat and reduce food waste, (2) increasing the proportion of vegetables on the plate (from 25% to 50% of the meal would be vegetables) and (3) an informative nudge where visual cues, such as signs and posters, highlight the benefits of vegetables and inform students about food waste.

All three strategies had some effect:

1. Decreasing the default portion size led to less food intake. However, this also meant less vegetable intake. There was no difference in food waste.
2. Increasing the proportion of vegetables on the plate led students consuming more vegetables, but at the same time also disposing of more vegetables. Interestingly, meat waste decreased but rice waste increased (while relatively, less rice was served compared to the baseline meal). Thus, in total there was an uptake in food waste when the students were served more vegetables.
3. Providing information about the issue of food waste prior to ordering food interestingly did not result in smaller food portions, but did result in less food waste. Positive messages about the personal gains available from additional fruit and vegetable consumption didn’t increase vegetable intake.
4. This study also investigated the effect of plate material: some studies suggested that more food waste happened with biodegradable plates compared to plastic ones. However, in this study no significant difference in portion size, intake or waste is identified. This one remains for further investigation!

Interestingly, the effect of the portion size nudge seems to indicate that students eat a certain proportion of the served food and not necessarily a certain amount of food because the served portion did not change the amount of food discarded. However when we look at the results of increasing the proportion of vegetables on the plate, it’s interesting to note that while less meat was disposed of, more rice was wasted. Moreover, more vegetables were consumed, but also more vegetables discarded. This indicates that in changing proportions of a meal, we should keep in mind the complementary relationship between elements of the meal. Do you eat your rice when there’s no meat left to complement it?

Informative nudging as holy grail after all?

The greatest reduction in food waste achieved by Qi et al. (2022) was using the informative nudge on food waste. This is surprising, since meta-analyses on nudges for healthy nutrition showed that informative nudges were the least powerful among nudges (Cadario and Chandon, 2020). Possibly, informative nudges are more effective in reducing food waste as this is a problem that has received less attention than nutrition, thereby the awareness is lower and information about the problem can have an impact.

Another recent study by Vidal-Mones et al. (2022) also focussed on reducing food waste, employing three different nudging strategies that were all related to providing information about food waste. Interestingly, this study separated informative nudging in three strategies related to various ways to communicate information to diners:

1. Visual strategies. Posters were placed in the canteen, showing (a) the menu of the day in order to generate beliefs and perceptions about their lunch experience, (2) a hunger traffic light to let students reflect on their hunger before choosing a portion, and (3) a poster teaching students how to properly eat an apple.
   
2. Participatory strategies. Canteen staff explained to the students (a) what they would eat that day, while calming them down before entering into the canteen and (b) teached them how to properly cut and eat the fruits included in the menu of that specific day.
   
3. Educative. In different educational settings, food waste was discussed. (a) the coordinator speech included a cue to make students reflect about the portion sizes they were going to order to the canteen staff, (b) talking about food waste in tutoring group time to provide students with information about food waste.

While all strategies reduced the amount of waste generated compared to the baseline, the educative strategies proved most effective, reducing waste with 10,5% on average.

Conclusion

Overall, studies suggest that nudging strategies can be effective in encouraging students to choose vegetables and waste less food in the school cafeteria. These findings have important implications for policymakers and educators looking to promote healthy and sustainable food choices in schools and other settings. It shows that simultaneously aiming at vegetable intake and food waste may be a difficult proposition for canteens. To decrease food waste, it’s important to communicate the problem of food waste to students both visually and verbally in tutor groups and speeches by authoritative figures. In order to increase vegetable intake, the most effective way is to increase the proportion of vegetables on the plate, but this also leads to more food waste.

These findings are of interest as in the past informative nudges have shown not to be effective in a lot of behavior change domains such as healthcare, energy consumption and traffic safety. In all these domains, it showed that awareness campaigns were only effective when the awareness of the problem was actually low in the target audience. Most of these problems did not necessarily have a problem of awareness and thus other nudges showed greater impact. Given the effects observed in the studies here, it seems that food waste may still suffer from a lack of awareness and therefore informative nudges could be a strong asset in reducing the unnecessary disposal of food.