Predictors of food waste quantities and composition: A nationwide diary study of Swiss households

In this study, we aimed to quantify the average amount of avoidable food wasted in Swiss households using a novel web-based diary method. We also aimed to identify under-explored predictors of food waste, including sociodemographic factors (e.g. linguistic region), psychological factors (e.g. plate-clearing tendencies and perceived health risk), and eating habits (e.g. dietary patterns and frequency of dinner preparation). We collected data from a random stratified sample of 515 households in Switzerland across three linguistic regions. Food waste data for 14 food groups were collected via a web application, whereas personal and household characteristics were gathered separately through online surveys. We identified food waste predictors using correlation and regression analyses. On average, the participants reported wasting 401.9 grams (standard deviation = 394.3) of food per capita per week. Overall, age, household size, linguistic region, and plate-clearing tendencies were key predictors of food waste. Households in Italian-speaking regions wasted less food than those in German-speaking regions. Additionally, participants with stronger plate-clearing tendencies wasted less food than those with weaker tendencies. This finding might thus highlight a relevant trade-off between reducing food waste on plates and increased overeating (metabolic food waste), which may result from a stronger tendency to clear one's plate. We also observed that 'non-meat eaters' generated more waste of starchy side dishes than 'meat eaters'. Our findings highlight the need for future interventions to address cultural, behavioural, and dietary factors to reduce avoidable food waste and offer insights for designing targeted strategies for specific populations and food categories.