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The 'Schools Don't Waste' Program: A Theory-Informed Participatory Intervention to Reduce Plate Waste in Public
Mariusz Jaworski1,2, Ewa Chojnowska2
1Department of Education and Research in Health Sciences, Faculty of Health Science, Medical University of Warsaw, 00-581 Warsaw, Poland.
Background/Objectives:
Food waste in school canteens constitutes a significant environmental, organizational, and public health challenge. Despite numerous initiatives aimed at reducing plate waste, limited evidence exists on participatory interventions grounded in coherent theoretical frameworks and implemented in real school settings. This study aimed to evaluate the effects of the Schools Don't Waste (SDW) program, a participatory, educational, and behavioral intervention based on the Needs-Based, Learner-Centered, Behaviorally Focused (NLB) model, in reducing visually assessed plate waste in primary school canteens.
Methods:
A quasi-experimental pre-post design without randomization was conducted in 37 public primary schools in Warsaw during the 2024/2025 school year. The intervention consisted of four stages: baseline plate waste assessment (T1), participatory roundtable meetings (T2), implementation of educational and organizational actions (T3), and post-intervention evaluation (T4). Plate waste was assessed using a standardized five-point visual scale. Differences between T1 and T4 were analyzed at the school level using the Wilcoxon signed-rank test. Implementation fidelity and its association with food waste reduction were explored using Spearman correlations.
Results:
A total of 4988 meals were assessed at baseline and 4080 at follow-up. Significant reductions were observed in the proportion of completely uneaten meals (Δ = -6.10 pp; p < 0.001; r = -0.67), meals with three-quarters uneaten (Δ = -5.76; p < 0.001), and meals with half uneaten (Δ = -7.97; p = 0.002). Overall uneaten meals decreased significantly (p = 0.004). Sixty-two percent of schools demonstrated measurable improvement, although fidelity indicators were not significantly correlated with outcomes.
Conclusions:
Participatory, low-cost interventions integrating educational and organizational components may effectively reduce plate waste in school settings, while structural and contextual factors appear to moderate intervention effectiveness.
