Assessing nutritional compliance, plate waste and menu acceptability in Spanish school meal programmes (ANPAS-Sp): protocol for an explanatory sequential mixed methods study.

The implementation of healthy, sustainable school menus represents a critical transition requiring strategic management to ensure nutritional compliance, student acceptability, and minimal food waste. Currently, evidence remains inconsistent due to a lack of validated protocols correlating nutritional standards with objective consumption data. Consequently, a comprehensive, explanatory sequential mixed-methods protocol is developed (ANPAS-Sp). It integrates a systematic nutritional audit (Phase 1) -aligned with Spain's Real Decreto 315/2025 and Catalonia's School Menu Review Programme-with high-precision direct weighing of plate waste and validated facial hedonic scales (Phase 2). Furthermore, the protocol employs targeted focus groups to qualitatively explore food rejection patterns identified after quantitative phase (Phase 3). This protocol facilitates evidence-based interventions and data pooling to advance sustainable school food systems. It spearheads a standardized evaluation framework for public health policies, establishing a new benchmark for gathering integrated evidence. Ultimately, this approach provides the necessary tools to transform school meal programs into healthy, widely-accepted, and zero-waste systems.•Approach: A standardised evaluation framework that empirically correlates the compliance of nutritional recommendations, the quantification of plate waste, and student acceptability of school meals.•Impact: It provides the necessary scientific tools to optimise school meal programmes and promote the transition towards sustainable school food systems.