Adherence
Doubling the proportion of vegetarian meal options available in a cafeteria from 25% to 50% significantly increases the selection and sales of vegetarian meals while decreasing meat meal sales, with the largest effect observed among diners with the lowest prior levels of vegetarian consumption.
To encourage more plant-based eating in a cafeteria, simply double the number of vegetarian dishes offered relative to meat dishes (e.g., from 1 out of 4 options to 2 out of 4). This simple change in availability significantly increases vegetarian sales, especially among those who rarely eat vegetarian meals, without negatively impacting total sales or causing rebound meat consumption at other meals.
Doubling the proportion of vegetarian meals available from 25 to 50% (e.g., from 1 in 4 to 2 in 4 options) increased vegetarian meal sales (and decreased meat meal sales) by 14.9 and 14.5 percentage points in the observational study (2 cafeterias) and by 7.8 percentage points in the experimental study (1 cafeteria)... Linking sales data to participants’ previous meal purchases revealed that the largest effects were found in the quartile of diners with the lowest prior levels of vegetarian meal selection.
Why this rating
Large-scale field study with 94,644 meals, combining observational and experimental designs with individual-level tracking.
Source
Impact of increasing vegetarian availability on meal selection and sales in cafeterias
Emma Garnett et al. · Proceedings of the National Academy of Sciences · 2019
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