Smaller servings vs. information provision: Results of two interventions to reduce plate waste in two university canteens.

Two interventions were systematically evaluated in two university canteens on their effectiveness to reduce visitors' plate waste. The evaluation was theory-based and focused not only at the effects on the amount of plate waste, but also at the psychological predictors underlying plate waste behaviour. In Intervention A, visitors received information about food waste over a period of three weeks. In Intervention B, in addition to information, smaller servings were offered. The actual amount of plate waste and visitors' attitudes, personal norms, beliefs, perceived behavioural control, intentions and plate waste reduction behaviour were measured before and after the interventions. Intervention B reduced the amount of plate waste by 20%, whereas no reduction was found after Intervention A. In both interventions, the provided information resulted in more positive beliefs and stronger personal norms regarding avoiding plate waste. The information also caused attitudes to have a stronger influence on plate waste reduction behaviour, whereas intention to reduce became less important for reducing plate waste. Personal norms regarding food waste were the strongest predictor of plate waste reduction behaviour, before and after the interventions. The provided information was thus insufficient to reduce plate waste, simply offering smaller servings could achieve this. Although our intervention study only included two university canteens and was conducted for a short period, our data seem to imply that a combination of both information and smaller servings reduces plate waste in the food service industry.