Abstract Background It is currently estimated that 1.3 billion tons of food are wasted in the world and that 14% of total waste comes from collective catering. Specifically, the percentages waste in school catering are highly variable, ranging from 11.9% to 27.5%. In order to deepen the phenomenon, ATS Val Padana has started a project in some middle schools in the areas of its competence. Objectives The project, started in 2016, was composed by 6 phases: 1) Nutritional inspection in schools to evaluate the waste; 2) Administering of a questionnaire to the students to evaluate the eating habits and opinions about the offered menu; 3) Selection of a pilot school; 4) Implementation of a new menu built on the basis of students' preferences; 5) Organization of 2-hour educational meetings for each class of the pilot school to educate students; 6) Nutritional inspection after menu modification and meetings. Results 7 schools were examined; 1335 students involved (of which 49.3% females). The total waste was on average 36%, with higher peaks related to the side dish (66%) and fruit (39%); the first dish remains the most popular dish with a waste of 14%. The school with the highest number of students enrolled in the canteen (152) was selected for menu modification and meetings. After about 3 months it was observed: a 11% reduction of the total waste. There was a statistically significant reduction in relation to the gap for the first and the side dish. For the second dish there was a 7% increase in waste. Conclusions The overall reduction of waste shows that targeted actions on menus, built on the basis of student preferences, can be an effective tool to reduce the food waste. Key messages An important percentage of waste comes from collective catering or from school catering. Menus, built on the basis of student preferences, can be an effective tool to reduce the food waste.