Demand-side interventions for sustainable food systems: A meta-analysis of food policy interventions targeting food consumption and waste behaviours

It is now widely accepted that a significant portion of emission reductions required to meet net-zero targets must come from individual behaviour change. Shifting consumers towards more sustainable food consumption and avoiding food waste have been identified as key levers to mitigate climate change and slow biodiversity decline. However, there remains a lack of knowledge on which food policy interventions can best harness this potential. Here, we use a rigorous, machine-learning-assisted systematic review and meta-analysis to comparatively assess the effectiveness of demand-side interventions targeting actual (or incentivised) food consumption and waste behaviours at the individual and household levels to comparatively assess the effectiveness of demand-side interventions targeting actual (or incentivised) food consumption and waste behaviours at the individual and household level. Based on 211 effect sizes comprising over 4.5 million observations, we find a small overall effect size across all food consumption interventions (z = 0.15), and a small to medium effect size for food waste interventions (z = 0.20). When accounting for moderate publication bias, these estimates are reduced to 0.10 and 0.18, respectively, but remain statistically significant at conventional levels. Our analysis reveals that, in both domains, structural choice architecture interventions are most effective in changing behaviour, followed by monetary incentives. Sensitivity analysis shows that the current evidence base is characterised by substantial heterogeneity across studies, which is not systematically related to variability in internal and external validity of studies. Our results underscore the necessity for future research to be carefully designed to uncover the factors determining when, how and why interventions are effective.