A behavioural pilot at a Prague workplace canteen tested four ways to encourage plant-based meals. One worked. The reasons the others did not are just as useful.
Earlier this year ISAAP published a qualitative study on what leads companies to choose plant-based catering. That research asked people what they believed. This follow-up asked a harder question: when a canteen actually changes what it puts in front of people, what happens to the trays? Over four months in 2026, researchers at Green Dock worked with Catering Zdravě and ProVeg Czechia to find out at Café Organica, a workplace canteen in Prague.
Four interventions, one canteen, four months
The team designed a package of four behavioural interventions and ran them through August 2026, with sales data collected for a full month beforehand (July) and a full month afterwards (September) for comparison.
- Three plant-based Mondays — on 10, 17 and 24 August, all main dishes on offer were plant-based.
- Protein labelling — the protein content in grams was displayed next to every plant-based option.
- A photo screen — a digital display in the canteen showed photographs of the plant-based dishes alongside the menu description.
- A half-price salad — diners choosing a plant-based main could claim a side salad at 50% off through a QR voucher.
The interventions were chosen at a co-design workshop with project partners in spring 2026, drawing on earlier qualitative interviews with canteen diners. Each was designed to be cheap, reversible and realistic for an ordinary food service operation to run — not a one-off showcase.
What the sales data showed
In August, plant-based meals made up 28.2% of everything sold, against 17.6% in July and 19.0% in September. On the face of it, a jump of more than ten percentage points.
The analysis then took that result apart. Almost all of the increase came from the three plant-based Mondays, days on which no meat dish was available at all. When Green Dock removed those days from the model, August’s plant-based share was statistically indistinguishable from any other month. The other three interventions — the labelling, the screen and the salad discount — produced no effect the data could detect.
Total meals sold fell slightly in August compared with July, which would matter a great deal to any operator considering plant-based days. The difference was not statistically significant, and August is a holiday month in Czechia, so the pilot cannot settle the question either way. It is one of the clearest gaps for the next round of testing.
What diners said
In September, 105 diners completed a survey about the changes. Nearly everyone had noticed the plant-based Mondays. Close to a quarter had not noticed the screen, the protein labelling or the salad voucher at all — which goes some way to explaining why those three left no trace in the sales data.
Among the 74 respondents who had eaten a plant-based meal, the dishes scored well on almost every measure: tasty, visually attractive, easy to picture from the menu, and mostly filling. The one clear gap was value. Close to half were not persuaded that a plant-based meal offered the same value for the price as a meat dish. That perception was closely tied to how filling people found the food and how much they enjoyed it, and it was stronger among diners who already eat plant-based regularly and among older diners.
The ranking of the interventions by satisfaction is worth sitting with. Protein labelling — the intervention with no measurable effect on what was sold — was the one diners liked most, and around six in ten wanted it kept from October. Plant-based Mondays, the only intervention that moved the numbers, were the most polarising and drew the most comments, mostly critical, and mostly from diners who prefer meat. Their objection was consistent and specific: not the plant-based food itself, but the loss of a choice.
Several themes ran through the written comments. Diners asked for protein content and photographs on the meat dishes too, not only the plant-based ones. They wanted more traditional Czech meat-free cooking — fruit dumplings, potato pancakes — alongside the tofu and tempeh. They pointed out that a side salad pairs oddly with a plant-based main that is already full of vegetables, and suggested a dessert instead. And a substantial group was simply enthusiastic, including people who otherwise eat meat.
What we are taking from it
Green Dock’s recommendations are practical and deliberately cautious.
Fully plant-based days work, but they come at a cost in goodwill that an operator has to weigh. Rather than abandoning the approach, the report proposes two alternatives worth testing: making plant-based the default while keeping a meat option available on request, or inverting the usual ratio on selected days — two plant-based mains and one meat dish, instead of the other way round. Both preserve the element of choice that diners defended so firmly, while still shifting what most people end up eating.
Protein labelling should continue. Its value is not that it sells more plant-based meals today, but that it helps diners decide with better information, and they appreciate it. The same logic applies to anything else that closes the information gap between plant-based and conventional options.
And the value perception finding points straight at the next piece of work. Plant-based meals in this canteen were not rejected for taste or appearance. They were questioned on whether they are worth the money. That is a solvable problem, and solving it is likely to do more than any single nudge.
Looking ahead
Green Dock is now preparing a handbook of behavioural recommendations for food service operators, due at the end of October 2026, together with a summary report that will feed into the project’s final evaluation. A series of workshops with organisations interested in applying these findings in their own canteens and catering follows after that.
We are grateful to Ondřej Kácha and the team at Green Dock for research that reports what happened rather than what we hoped would happen, and to Catering Zdravě for opening a working kitchen to a month of measurement. Our work in Czechia under ISAAP sits alongside legume value chain development in Portugal and healthcare professional engagement in Denmark, all of it pointing towards the same goal: healthier diets, lower emissions, and more resilient food systems.
The handbook and the summary report will be published at isaap.eu when they are ready.