Sustainable Healthy Diets and Pathway to Net Zero: Assessing the Role of Dietary Transitions in UK Food System Decarbonisation

Scope Defra is seeking to commission a research project to quantify how a transition to more sustainable and healthy diets, driven by current consumption trends and potentially enhanced by future demand side policies may influence UK territorial greenhouse gas (GHG) emissions from the food system in the run up to Net Zero 2050. The study should explore a suite of policy driven and trend driven dietary transition scenarios and assess consequential effects on: • UK agricultural production patterns • Trade flows and import/export exposure • Land use and land use change • Herd sizes and protein production • Energy use and food system infrastructure • Broader system feedbacks (market responses, consumer acceptance, technological shifts) The project is expected to address these issues through robust modelling, integrating economic, system-dynamic, behavioural, and physical modelling where appropriate, and using both attributional and consequential Life Cycle Assessment (LCA) approaches. Required Expertise Suppliers (or consortia) should demonstrate: • Technical expertise in food systems sustainability, greenhouse gas accounting, systems modelling, life cycle assessment. • Advanced modelling capability, including development and/or application of: o Systems dynamics models o Agent-based models o Integrated assessment or economic models o Other complex modelling frameworks appropriate for long term scenario design • Ability to synthesise evidence using government standard approaches, including Quick Scoping Reviews and Rapid Evidence Assessments. • Critical appraisal skills to articulate uncertainties, limitations, methodological trade-offs, and data gaps. Consortia and collaborations with academia, research institutes, NGOs, sectoral bodies, and industry partners are welcomed. Additional Context This project is informed by a growing evidence base demonstrating that demand side dietary change is likely to be essential for meeting the UK's Net Zero goals, as supply side agricultural efficiencies alone are insufficient. However: • Existing UK modelling often uses outdated datasets, • Many studies apply simplified trade assumptions, and • Few explicitly model the pathways from policy → consumer behaviour → production → territorial emissions. This project intends to fill these gaps by developing a credible, future facing modelling framework capable of capturing complex interactions across the food system and assessing the role of different policy packages. Defra has separately commission ADAS to examine the climate implications of market expansion in the UK alternative protein sector (outputs expected May 2026). Alignment between this study and the AP study is encouraged.