PI: Maya Mathur

Date Awarded: April 2022 (FSRF 2021-12-01 & 2023-02-08)

Summary :

Key Findings

We tested the effectiveness of a default nudge, meaning that the meat in the staff-served plated meal (which also included food items other than meat) was a reduced portion size by default

• This reduced meat portion size was achieved by reducing the size of the spoon used to serve the meat, which simply means swapping the standard serving spoon for a smaller size

Importantly, besides measuring meat consumption, we also measured metrics such as diner satisfaction and potential backfiring effects from diners, which are crucial metrics for the food service industry

Implementation in a university dining hall underscores the real-life applicability of this study, as the college dining hall is a food service model very similar to other popular models such as workplace cafeterias, school canteens, and staff-served restaurant chains

Our first study found that a 25% spoon-size reduction (from 4oz to 3oz) resulted in ~18% less meat consumed

• This dish was made-to-order burritos, which always included one type of meat and other ingredients that the diner could customize, such as rice, beans, and vegetables

• The estimated effect of this intervention was 24 lbs less meat consumed on a daily basis

• There were no meaningful differences in diner satisfaction and fullness

Our second study found that a more substantial 50% spoon-size reduction (from 4oz to 2oz) did not work

• This dish had more varying menu items, such as Korean chicken and tuna melt sandwiches

• The intervention triggered backfiring effects, including increased meat consumption at dinner depending on the specific menu item and the intervention significantly increasing the odds of diners reporting that they ate meat as part of their meal

• Furthermore, diner satisfaction and diner fullness significantly decreased while diner hunger significantly increased

Recommendations

In order to implement this intervention, the meat has to be scoopable with a serving spoon

‘Less is more’ - the more subtle 25% spoon-size reduction was more effective than the more drastic and visually salient 50% reduction

The type of dish matters: if the meat is concealed (e.g., inside a burrito), the reduced meat portion size is easier to conceal

The size of dish also matters: burritos are usually a larger meal and can thus still be filling despite the reduced meat portion size within them

Given that protein is the most satiating macronutrient, future studies should explore compensating with plant-based protein to offset diner hunger in default portion size interventions

Further Information: Study preprint is available here. Publicly available dataset, code, materials can be found here.