are the kids eating the plant-based meals in the long run, or they bring meat sandwiches from home for that day, because they donât like the plant-based alternative; or they eat extra meat at home in the evening to compensate for the lack of meat at school that day;
(...)
I hope this will give you a sense of how you can go about it, because there is only one study on this type of intervention and if I remember correctly it was either not effective at all or barely effective. Hopefully, someone will find a link, so you can check how they went about the calculations.
Hereâs some relevant research and writing Iâve come across, but they donât seem to estimate effects on meals at home:
More skipped meals (when allowed, depending on the school level), plate waste and eating less on vegetarian days in the short term (and pretty significant effects, like 18%-40% for each), while in the medium term, only eating less on veg days and skipping meals but also students eating more vegetarian meals on other days. It seems reasonably likely these students would eat more meat at home on average to compensate, but I donât think this would cut the cost-effectiveness down by more than half.
I would assume they donât fully compensate on average and they would do so less in the long run, but I donât know how much they do (or whether some eat even fewer animal products at home), and this is something worth looking further into. There is research on rebound effects for voluntary (including nudging) meat reduction interventions (mostly seem small, from what Iâve seen), but we probably shouldnât generalize from it, given how differently people react to being forced to do something.
The parents would also have a say on whether or not the students would eat more meat after school to compensate. They might encourage it or discourage it.
Hereâs some relevant research and writing Iâve come across, but they donât seem to estimate effects on meals at home:
Forced Choice Restriction in Promoting Sustainable Food Consumption: Intended and Unintended Effects of the Mandatory Vegetarian Day in Helsinki Schools
More skipped meals (when allowed, depending on the school level), plate waste and eating less on vegetarian days in the short term (and pretty significant effects, like 18%-40% for each), while in the medium term, only eating less on veg days and skipping meals but also students eating more vegetarian meals on other days. It seems reasonably likely these students would eat more meat at home on average to compensate, but I donât think this would cut the cost-effectiveness down by more than half.
Nutritional quality and acceptability of a weekly vegetarian lunch in primary-school canteens in Ghent, Belgium: âThursday Veggie Dayâ | Public Health Nutrition | Cambridge Core
Differences in plate waste were small enough to ignore.
Meat Reduction by Force: The Case of âMeatless Mondayâ in the Norwegian Armed Forces
Vox: A French city announced it would serve meatless school lunches. The backlash was swift.
I would assume they donât fully compensate on average and they would do so less in the long run, but I donât know how much they do (or whether some eat even fewer animal products at home), and this is something worth looking further into. There is research on rebound effects for voluntary (including nudging) meat reduction interventions (mostly seem small, from what Iâve seen), but we probably shouldnât generalize from it, given how differently people react to being forced to do something.
The parents would also have a say on whether or not the students would eat more meat after school to compensate. They might encourage it or discourage it.