Which government policies to create healthy diets from sustainable food systems have the potential to simultaneously address undernutrition, obesity and environmental sustainability? Results of an evidence review and international expert consultation.

Abstract Introduction: A transformation of food systems is urgently needed, given their contribution to three ongoing and interlinked global health pandemics: (1) food insecurity, (2) obesity and non-communicable diseases (NCDs), and (3) climate change and biodiversity loss. As policymakers make decisions that shape food systems, this study aimed to identify and prioritise policies with double- or triple-duty potential to achieve healthy diets from sustainable food systems (SFS). Methods Through a compilation of international policy recommendations, a scoping review, online surveys and four regional workshops with experts, policies were identified and prioritised based on their double- or triple-duty potential, synergies and trade-offs. Using participatory and transdisciplinary approaches, policies were identified to have double- or triple-duty potential if they were deemed effective in tackling two or three of the primary outcome areas of interest: (1) undernutrition, (2) obesity/NCDs and (3) environmental sustainability. Results A list of 44 proposed policies for healthy diets from SFS was created, divided into two main policy domains: ‘food supply chains’ and ‘food environments’. Four synergies and 32 trade-offs were identified. The outcome area with the most trade-offs identified was ‘undernutrition’, followed by ‘environmental sustainability’, and ‘obesity/NCDs’. Of the top five expert-ranked food supply chain policies, two were perceived to have triple-duty potential: (a) incentives for crop diversification; (b) support for start-ups, and small- and medium-sized enterprises. For food environments, three of the top five ranked policies had perceived triple-duty potential: (a) affordability of healthier and more sustainable diets; (b) subsidies for healthier and more sustainable foods; (c) restrictions on children's exposure to marketing through all media. Conclusion This study identified and prioritized a comprehensive list of double- and triple-duty government policies for creating healthy diets from SFS. As some proposed policies may have trade-offs across outcome areas, they should be carefully contextualised, designed, implemented and monitored.