Food waste is not fought solely through awareness campaigns. This is one of the conclusions of the European project COMBINE, which tracked wasted food for more than a year at the Aprendizes school in Cascais and in the homes of the students’ families. Coordinated in Portugal by professors Iva Pires and Sónia Nobre, from NOVA University of Lisbon, the project tested different measures to understand how information and practical actions can change behaviours. In the participating families, food waste decreased by 33% after the intervention, dropping from an average of 89.8 to 40.2 grams per meal. In the canteen, however, the initiatives increased students’ willingness to waste less, but did not translate into an actual reduction in food left on the plate.
In an interview with Green Savers, Iva Pires emphasizes that prevention requires responses tailored to the causes of waste in each context. At home, the tested measures helped families plan purchases and meals better, adjust portions, preserve foods and make use of leftovers. At school, awareness alone was not enough to change outcomes, underscoring the importance of adjusting portion sizes and creating conditions that facilitate different choices. The researcher thus advocates an approach that involves schools, families and public entities, with concrete and ongoing measures. More than merely alerting to the problem, it is necessary to create conditions for reducing waste to become part of daily routines.
The COMBINE project starts from the idea that food waste should be fought in the various contexts in which we eat. Why did you decide to study the relationship between what happens at the school table and the habits of families at home?
The project’s objective is to contribute to the reduction of consumer food waste by combining different types of actions in various settings of daily life, specifically in schools, workplaces and households. It was important to combine actions in several locations because, according to some studies, this fosters the creation of habits and behaviors that are more coherent and consistent with the aim of reducing food waste. Moreover, data from the European Union, including Portugal, show that the majority of food waste occurs at the end of the supply chain, as a result of consumer behavior, whether at home or away from home. According to INE data, it is estimated that in Portugal, in 2024, 1.8 million tonnes of food were wasted and 65.1% of this waste occurred in households, which corresponds to about 1.2 million tonnes of food. Consequently, intervention at the household level is very pertinent.
Although only a very slight reduction in waste per capita was observed in Portugal between 2022 and 2023, it rose again in 2024.
For more than a year, you monitored food waste at the Aprendizes school and in the students’ families’ homes. What did the initial weighings reveal and what were the main foods wasted?
In the first phase of the project, the diagnosis of food waste at Aprendizes’ canteen, the project’s partner school in Portugal, was carried out by quantifying the waste generated by primary, middle, and secondary school students over 10 days. This process was successfully carried out thanks to the support and invaluable collaboration of the kitchen team, especially in reorganizing the service, counting the students served each day, weighing the food waste, providing the menus, and resolving various logistical issues.
The initial weighing revealed that the average waste generated by students was 14.97 kg, oscillating between a minimum of 9.67 kg (on the 8th day) and a maximum of 28.51 kg (on the 9th day). The average waste in grams per meal was 38.3 g/meal. Globally, older students (middle and high school) wasted more food than the younger ones (primary). The good news was that the majority of Aprendizes students left a low or zero volume of waste on their plates (70.8%), with the remaining 29.2% leaving a medium or high volume of waste. The foods wasted varied according to the menu, but the largest total volume of waste occurred on the day of a themed menu in which the foods had a stronger flavor than usual. The main reasons reported by the students for the waste generated were dissatisfaction with the cafeteria food and serving too much food on the plate.
At the family level, the first phase of the project included weighing at-home food waste over a week. Families were given a kit that included a scale, two small containers for food waste, and instructions for counting and recording waste. The management of contacts with families and the support of the Aprendizes secretariat in delivering the materials needed to weigh food waste at home were fundamental to executing this stage of the project.
The initial weighing revealed that the average waste generated by families was 4.2 kg, ranging from 1.7 kg to 10.1 kg. The average waste per meal by families was 89.8 g/meal.
The foods wasted varied among families but notable were the inedible leftovers inherent to meal preparation (e.g., vegetable peels), perishable foods (fruits and vegetables), and leftovers from dishes.
What solutions were tested throughout the project and which had the most significant results? Was there any change that surprised you by its effectiveness?
The actions implemented were based on the results obtained from the diagnostic and focused on the main causes of food waste identified.
At Aprendizes, these actions included: workshops for students where the results of the canteen waste quantification were presented and discussed; kitchen team support to help students serve proper portions of food; production of posters about food waste and proper portions displayed in the canteen; a targeted action with a reward (dessert) if there was a reduction in canteen food waste in a second quantification phase compared with the initial diagnostic value; creation of a video on this topic by the students, aiming to inform and contribute in a creative and appealing way to reducing colleagues’ food waste; and an internal session about the food served in the canteen.
The dessert-offer action was the one that most excited and motivated the students to reduce food waste, and the posters are expected to have generated a greater impact on the students involved in their creation. Globally, the actions implemented at Aprendizes increased students’ willingness to reduce food waste.
However, there was no reduction in school food waste, which may be due to several factors, namely: the students, especially the older ones, continued to serve themselves oversized portions of food; and the canteen menu did not change substantially.
Families received four newsletters on various topics related to food waste and participated in a workshop with tips and demonstrations of recipes for reusing leftovers and full utilization of foods. This workshop took place at Aprendizes and was designed and organized in conjunction with several school professionals, notably the head of the kitchen team and the nutritionist, who played a crucial role in the success of this initiative. The workshop was especially valued for its practical and interactive component. There was a 33% reduction in family food waste, translating into an average of 40.2 g/meal after the intervention.
One of the objectives was to understand whether what children learn or change at school is reflected in family behaviors. Do the results allow concluding that this influence exists? What concrete changes did you observe at home?
This project aimed to stimulate and strengthen the link between school and families regarding food and food waste, particularly through its methodology and the family workshop that took place at Aprendizes. National results and those from other countries underscore the importance of involving the various members of the family, including children, in raising awareness about food waste and adopting measures to reduce it. The data suggest that a family-centered approach promotes engagement, reflection, and shared responsibility to reduce food waste.
In Portugal, 65% of food waste occurs in households, according to INE data from 2024. Which domestic behaviors or routines continue to contribute most to this problem, and what can help to change them?
According to the results of this project, the main causes of household food waste include waste generated during meal preparation (inedible), forgotten foods that spoil, doubts about whether certain foods can be safely consumed, unused leftovers, buying and cooking more food than needed, and putting too much food on the plate.
It is necessary to raise families’ awareness of the waste they generate at home and stimulate collective reflection on what it means, in environmental, economic, and ethical terms, to throw food in the trash. Moreover, it is necessary to foster knowledge, motivation, and the capacity of families to adopt measures that contribute to reducing food waste in terms of purchasing, planning and preparation of meals, portions served on plates, use of leftovers and storage of food. Involvement of the whole family and shared responsibility in reducing food waste should be promoted. It is important to provide simple, feasible, and sustainable tips. Practical and interactive approaches, for example with demonstrations of recipes using leftovers, seem more appealing to families and more effective in reducing food waste.
To what extent can children influence the adults’ decisions, from meal planning and shopping to food storage and use of leftovers? Did the project find concrete examples of this influence?
Overall, the participating families were concerned about food waste, already had some habits that contributed to reducing it, and conveyed them at home to their children. Participation in this project increased their awareness of the problem and contributed to the adoption of more measures to reduce food waste. The results of this project emphasize the importance of education for reducing household food waste and involving children in food-related tasks, for example in planning purchases, since most studies point out that planning purchases is a good practice to reduce food waste, and in discussing appropriate portions of food served to them.
Beyond awareness, how important were the practical measures tested in the project? What do the results say about the difference between knowing we waste food and actually changing our habits?
In school, raising students’ awareness and their willingness to reduce food waste did not translate into an actual reduction in waste, perhaps making some changes to the menu and creating a more favorable and facilitating environment for serving appropriate portions of food would be necessary.
In families, awareness of this problem was accompanied by adopting concrete measures to reduce food waste, particularly in purchasing and meal planning (e.g., buying fewer perishable foods at a time), cooking and consuming meals (e.g., cooking and serving more appropriate portions), food storage (e.g., checking the fridge more regularly), and using leftovers (e.g., making recipes with leftovers inspired by the workshop). For these measures to be effective, they must be realistic, feasible, simple, tailored to each family context and ideally accepted and adopted by all members of the household, so as to be more easily incorporated into family routines.
What difficulties did you encounter in implementing the measures, both at school and with families? Were there differences in how participants adhered to the proposed solutions?
The partnership with Aprendizes was crucial to the realization of the project, highlighting the school’s availability, commitment, interest, and facilitation of this process, resulting in a highly fruitful, rewarding, and enriching collaboration. The school actively contributed to implementing all stages of the project, including idea sharing, resource provision, carrying out various activities, and the direct mobilization and involvement of professionals from various areas, including the leadership, cycle coordination, teaching, the kitchen team, the nutritionist, communications and marketing, and the secretariat. However, there were challenges in scheduling and implementing some actions, due to the multiplicity and overlap of activities in the school.
The participating families were receptive, committed, and available to collaborate, but it was challenging to maintain their participation throughout the project. In addition, some families considered weighing food waste to be a burden in terms of work and time.
Do the results allow us to determine whether the behavior changes persist over time, or is longer-term follow-up necessary to assess their durability?
In follow-up interviews with families (3-4 months after the actions were implemented), all expressed their intention to maintain the measures over time to reduce food waste. Some families stated that these measures will be lasting because they have become naturalized and consolidated in family dynamics. In the case of the school, the initiatives implemented contributed to a better awareness of food waste, but this did not translate into a reduction in its volume.
The COMBINE involves partners from four European countries. What conclusions do you draw from the Portuguese experience and what aspects could be applied in other contexts, considering differences in eating habits and the organization of schools and families?
In partner schools, as in Portugal, the main causes of food waste were students’ dissatisfaction with the cafeteria food and portions that were too large. Unlike Portugal, in partner schools students are served by staff, which allowed greater control over the portion sizes served, which had a direct impact on the weighings and contributed to the reduction of food waste in those schools. In cases where students serve themselves (as at Aprendizes), it is necessary to reinforce mechanisms that promote and facilitate students serving themselves appropriate portions.
The results for families in partner countries are similar. However, in Portugal there is a greater prevalence of food waste (inedible) generated during meal preparation, indicating that all families participating in the Portuguese context usually cook at home. The family workshop provided tips and demonstrations on making use of these types of leftovers and could be replicated in similar contexts.
What would be necessary to replicate this approach in other Portuguese schools? What role should schools, families, municipalities, and public policy bodies play in reducing food waste?
It is necessary to outline in advance a realistic and feasible action plan that fits the school calendars and dynamics. The openness and commitment of schools to collaborate with such projects is essential. Often there is interest, but teachers’ overloaded schedules do not facilitate the implementation of yet another project. Communication must be clear and close, ideally with a preferred point of contact. The realization of this project at Aprendizes was largely due to the tireless and invaluable commitment and collaboration of the school’s pedagogical director. It is also worth noting the role played by the rector in pursuing the project, having shown great interest and openness to its realization and a attentive and constructive presence in the actions carried out. The execution of the actions depended on time, collaboration, commitment, creativity, and expertise of several school professionals, including cycle coordinators, teachers, the kitchen team, and the communications and marketing team.
It is necessary to contact families in advance, maintain regular and close communication to ensure their continued participation in the project, facilitate and simplify the actions they must perform, propose appealing initiatives adapted to family contexts, provide clear and concise instructions (for example for weighing food waste at home), as well as suitable support material, and be available to clarify questions or issues that may arise.
Reducing food waste requires shared responsibility among schools, families, and public authorities. More than raising awareness among citizens, it is necessary to create conditions to prevent waste throughout the entire food system.
Schools can promote sustainable eating habits, monitor waste in canteens, adjust portions, and involve students in awareness-raising about food waste and its environmental, economic, and ethical implications. Families can contribute through planning purchases and meals, proper food storage, and use of leftovers, although these practices are often constrained by income, time, and the food offered. Public policy bodies should set objectives, support research, and finance prevention measures, promoting cooperation among the different players in the food supply chain. It is essential to address the causes of waste, prioritizing prevention rather than focusing the response solely on waste management.
After the results now presented, what is the main conclusion you would like to leave: what can we start doing differently, at school and at home, to waste less food?
The results of this project suggest that food waste can be reduced through well-designed, complementary interventions in different contexts. The evidence suggests that actions are more effective when they facilitate reducing food waste at the moment of decision-making, address the causes of food waste in each context, and actively involve participants throughout the process.
In schools, it is necessary to combine strategies: increase students’ knowledge and awareness of food waste; adopt measures aimed at the causes of food waste; create an environment conducive to reducing cafeteria waste; maintain the initiatives over time; tailor interventions to students’ age groups; and directly involve students in this process.
In families, the interventions that promoted the reduction of food waste were adapted to family contexts and dynamics and involved awareness of the problem and the development and consolidation of skills to do so. The practical and interactive interventions were the most valued by families, and the involvement of the entire household contributed to reflection and shared responsibility in reducing food waste.
