The effect of student age on plate waste in Latvian primary and lower secondary school settings

Food waste (FW) is a critical global sustainability issue. The consumption stage—including school catering—accounts for over half of all FW generated across the food supply chain and represents a key setting where FW must be addressed. This pilot study assessed plate waste (PW) in four Rezekne (Latvia) schools (S1–S4) and its variation between primary (grades 1–4, aged 7–10) and lower secondary (grades 5–7, aged 11–13) students. All schools employed a partly pre-served catering model with fixed portions and no choice of dishes or sizes. A unified menu was applied across all schools and repeated during each data collection period to ensure comparability. The analysis focused on filtered PW, including only staples and meat/fish dishes and excluding inconsistently served items. In total, 17, 144 plates were surveyed across three measurement periods during the 2023/2024 study year. A two-way ANOVA revealed a significant age effect on filtered PW, with younger students wasting more food on average than older ones. No significant month effect or age–month interaction was found, indicating consistent age-related PW differences. Younger students generated significantly more PW in S1–S3, but not in S4, likely due to a smaller PW gap. These findings underscore the need for age-specific interventions, such as smaller portions for younger students or repeated exposure to less-preferred foods to expand their taste preferences and promote more sustainable eating behaviour.