Does adding a second vegetarian option change what people order?
The short answer
It does, in canteens. Doubling the share of vegetarian options raised vegetarian sales by about 8 to 15 percentage points without reducing total sales, and only about 6% of diners noticed. But a similar trial changing the order and the dish of the day found nothing at all.
The claim
“People order what they want. Changing the menu around them just annoys the customers who came for the steak, and the ones who wanted a vegetarian dish were going to order it anyway.”
Why this question comes up
- It matches how choosing feels from the inside: you look, you decide, you order.
- Caterers have watched plenty of well-meant menu changes fail, and some of them have annoyed customers.
- Behavioural interventions have a reputation, partly earned, for being oversold.
What the evidence says
Across 94,644 meals in university cafeterias, raising vegetarian options from a quarter of the menu to a half raised vegetarian sales by roughly 15 percentage points observationally and 7.8 points experimentally.
A French replication found the odds of a vegetarian choice rose about 2.6 times, and satisfaction went slightly up rather than down.
Only about 6% of diners in that replication noticed the menu had changed.
Nykänen and colleagues tested dish-of-the-day and menu-sequence nudges in a similar setting and found no effect on dish choice or on the weight of meat served.Source 1: Impact of increasing vegetarian availability on meal selection and sales in cafeteriasSource 2: Increasing vegetarian availability in a French university restaurantSource 3: Nudging towards plant-based main dishes in a university restaurant
Weighing the claim
What is true about the claim
- People do order what they want. Availability changes what is in front of them when they decide.
- Total sales did not fall in the cafeteria study, so this is not a trade of custom for virtue.
- Not every menu change works. The nudges that failed, failed cleanly.
What may be misleading
- The observational figure of 15 percentage points is roughly twice the experimental one. Quoting the larger number as what to expect would be overselling.
- Both availability studies are university catering with a captive audience eating there most days. A restaurant with a one-off customer is a different proposition.
- Availability worked; sequence and dish-of-the-day did not. 'Nudging' is not one thing, and the results do not transfer between them.
What remains uncertain
- Whether the effect holds in commercial restaurants, workplace canteens and supermarkets, where the audience and the alternatives differ.
- How long it lasts. The studies measure weeks and months, not years.
- Whether the effect depends on the quality of the added dishes, which no study has isolated.
Bottom line
If you set a menu, the share of plant dishes on it is the strongest lever the evidence supports, and it works without anyone noticing. Plan with the experimental figure of about 8 percentage points, not the observational 15, and do not assume other menu tricks will do the same.
Evidence strength
Why this rating: Consistent direction across two countries in a large field study and a replication, offset by a null result for other menu changes in the same kind of setting and by the gap between the two estimates in the original study.
Supported by good-quality studies that point the same way, but with gaps: fewer studies, mostly observational data, or some inconsistency.
Claims behind this answerEach claim has its own record with rating, methodology and sources.
Increasing the share of plant-based options on a menu increases the share of plant-based meals sold, without reducing total sales.
Yes, in canteen settings. Doubling vegetarian availability raised vegetarian sales by roughly 8 to 15 percentage points, and almost nobody noticed the change.
Naming a dish for its flavour rather than for what it lacks or for its health properties increases how often it is chosen, with the food unchanged.
Yes. Identically prepared vegetables were chosen 41% more often under a flavour label than a health-restrictive one, and 'meat-free' performed worse than almost every alternative tested.
Sources
Each source links to our record of what it found, its limitations and what we used it for, with a link to the original.
- 1Impact of increasing vegetarian availability on meal selection and sales in cafeterias
Emma S. Garnett, Andrew Balmford, Chris Sandbrook et al. (2019). Proceedings of the National Academy of Sciences.
- 2Increasing vegetarian availability in a French university restaurant
(2023). French university catering research group.
Peer Reviewed StudyRandomised Controlled TrialModerate evidence - 3Nudging towards plant-based main dishes in a university restaurant
(2022). University research group.
Peer Reviewed StudyRandomised Controlled TrialModerate evidence