Measuring household food waste at national level: a systematic review on methods and results.

Abstract The majority of food waste is generated at the consumption stage. Research on consumer food waste is increasing very fast, as well as the effort in the quantification of the amount of food waste generated at home. This review analyses the most relevant studies in this regard with the aim of (i) reporting the main findings on the amount of food waste generated at the household level, and (ii) comparing estimates from studies conducted with different methodological approaches, to highlight possible influences of methods over the findings. Despite the growing interest over the topic, the number of studies providing a quantitative estimation of household food waste is not very high, with 16 studies conducted in Europe and 3 in other countries. The main methods used are inference on national statistics about food and waste flows, and direct measurement, e.g. questionnaires, food diaries and waste compositional analysis. Results of household food waste vary from only 5 to over 100 kg per person per year. Such variety is due to the definitions of food waste adopted (limiting or not the focus on edible food waste), as well as to the different methodological approaches. While inferential studies' findings are somewhat comparable with results of food diaries and waste compositional analyses, the amount of food waste self-reported by respondents in questionnaires is always much lower, probably due to self-indulgency of respondents or to cognitive bias. These pieces of evidence suggest that further research on the quantification of food waste at the consumer level should adopt more reliable methods and use a consistent definition of food waste.