Small Plates, Big Impact: How Plate Size and Social Cues Affect Food Waste

What unsustainable behavior needs to change:

You may have seen videos of tourists frantically piling up food on their plates at hotel buffets. Unfortunately, this gluttonous behaviour contributes to the significant issue of food waste. Buffets are designed to offer a wide variety of options catering to different tastes and preferences. By design, the self-serve nature of buffets can lead to people taking more food than they can eat, as there are no portion control measures in place. 

If people do not fill up their plates with as much food as possible, they might feel as though they’re losing out on the opportunity to try a variety of foods or getting their money’s worth. One potential psychological explanation for this behaviour is called “Loss aversion.”

Additionally, people may also experience social pressure or expectations to consume more food when surrounded by others who are overfilling their plates. This can lead to a sense of conformity or a “fear of missing out” if one doesn’t fill up their plate in the same way; thereby worsening the problem of food waste.

The Green Nudge:

Norwegian researchers Steffen Kallbekken & Håkon Sælen wanted to see if they could nudge hotel guests to waste less food by changing the way the food was presented. In two treatments, the researchers manipulated external cues to measure their impact on average food waste (in kg). 

In the first treatment they reduced average plate size from 24 to 21 cm, combining a social cue (plate shape and size delineate norms for appropriate amounts of food to eat at a meal) with a visual illusion (smaller plate size can lead to biassed perceptions of how much food is consumed or served).

In the second treatment, they provided a more direct clue by displaying a sign at the buffet. It reads “Welcome back! Again! And again! Visit our buffett many times. That’s better than taking a lot at once.” This signal indicates that it is socially acceptable to serve yourself more than once. 

The results were impressive. Reducing the plate size led to a 19.5% reduction in food waste, while the sign at the buffet led to a 20.5% reduction. 

While the study has some limitations, such as a small sample size, the findings were supported by their own observational study and other studies that show how social influence or plate size can affect food behaviour.