Malnutrition in all its forms broadly includes undernutrition (e.g. underweight and lack of certain key nutrients) and overnutrition (e.g. obesity and related chronic non-communicable diseases, such as type 2 diabetes). Malnutrition in all its forms is the largest cause of disease and premature death globally and in South-East Asia (SEA). Its health impacts are twice as high as that of tobacco use and high blood pressure. This public health challenge is also associated with heavy social and economic burdens. Different forms of malnutrition share common causes, especially within food systems that are promoting these various forms of malnutrition, which can co-occur in the same individual, household or country at the same time. Locally relevant solutions will need to be generated in relation to people's eating habits and food cultures (e.g. the local food systems) as well as general living environments. Therefore, the seemingly different nutrition problems can be improved through common solutions targeting the wider systems of people's daily lives. Current approaches to interventions are not reducing undernutrition fast enough and have failed to control the rise of obesity and related chronic diseases. These problems have rarely been considered and managed together in an integrated way. To effectively combat this largely preventable public health challenge, we need a new way of working that recognises the connections between different forms and causes of malnutrition within a wider context and creates double-duty actions to address them together. We aim to develop public health interventions in Chinese and SEA cities that are: 1) jointly enacted by multiple sectors, 2) aimed to improve multiple forms of malnutrition, and 3) expected to benefit everyone living in these cities. We will do this collectively with local policy makers from different departments and sectors as well as community representatives (e.g. those who have delivered or received existing services or programmes aimed to improve nutrition status) over three project phases using a contemporary research method called the Group Model Building (GMB). GMB is a useful tool to develop a shared understanding of complex, inter-related issues and to facilitate coordinated actions among different people. It has been successfully used by members of this research team for developing systemic-level obesity interventions in developed countries. The proposed project (phase 1) will provide a strong foundation for subsequent project phases by: 1) co-developing systems interventions through GMB and forming intervention delivery Action Groups with local decision makers and community representatives in an Asian city; and gaining practical insights into this new intervention development method for application in other Asian cities, 2) identifying strategies to recruit SEA cities to join the project, and 3) providing information needed to support the development of an internationally comparable and sustainable tools to monitor and assess impacts of developed interventions. In the subsequent, phase 2 project, we will 1) support the Action Groups to deliver the interventions developed in phase 1, and measure early impacts of the interventions in the first Asian city using monitoring systems informed by phase 1; and 2) recruit SEA cities, develop interventions in these cities using the GMB process and form Action Groups. This will be the first research project to use GMB to develop malnutrition interventions in developing, Asian countries. Our findings will importantly advance the work on the Decade of Action on Nutrition towards achieving the United Nations' Sustainable Development Goals and contribute to method development and impacts of this new way of working on public health promotion globally.

We aim to develop multi-sectoral, double-duty, population-level interventions to reduce malnutrition in all its forms in Chinese and South-East Asian (SEA) cities through a systems-based, co-creation approach with local policy makers that we have successfully applied in other parts of the world for obesity prevention. The overall study has three phases. Phase 1 (this proposal) has three specific objectives, addressing important, early-stage research questions in a multi-nation intervention development process. Objective 1: To co-develop systemic malnutrition interventions through Group Model Building (GMB) and form delivery Action Groups with local decision makers and community representatives in a strategically chosen Asian city (Nanning); and gain practical insights into this new intervention development method for application in SEA cities. With support from the provincial government of the Nanning city (confirmed project partner), we will run three GMB workshops with leaders of diverse subsystems of the city's food systems and urban environments to understand complex connections between different drivers and forms of malnutrition in order to identify and prioritise systemic interventions. A Scientific Advisory Board of international experts of areas relevant to malnutrition interventions, and local experts and community representatives will participate in the last workshop to help define the details for locally identified and prioritised interventions. Anticipated outcomes: 1) Systems maps of the causes of malnutrition in all its forms and a Logic Model of multi-sectoral, double-duty interventions aimed to reduce the double burden of malnutrition in Nanning will be co-created with local decision makers who have the power to act and visualised as Causal Loop Diagrams. This will form a positive example, encouraging participation from other Asian cities in the subsequent study (phase 2). 2) Lessons learnt from the first GMB process in Nanning will inform the application of this new method for developing public health interventions in other Asian cities in the subsequent study. 3) The Action Groups (which comprise leaders and stakeholders of local departments or sectors relevant to agreed intervention themes) will be formed to deliver the interventions designed by themselves in the subsequent study, closing the crucial gap between intervention development and delivery. Objective 2: To explore strategies to recruit SEA cities to join the study with senior officials from SEA countries by sharing lessons learnt from the GMB based intervention development work in Nanning at a China-SEA Nutrition Forum, purposively organised with our strategic governmental partner for the SEA region. Anticipated outcomes: Feasible strategies identified to maximise the success in recruiting SEA cities to join the subsequent phases of the study. Objective 3: To inform the development of an internationally-comparable, sustainable intervention monitoring mechanism by exploring current malnutrition surveillance practices within 12 Asian cities (Nanning and one city from each of the member states of the Association of Southeast Asian Nations and from Sri Lanka) and the views of health authorities in these cities about adopting, adapting or extending established, international monitoring systems. Anticipated outcomes: Contextual knowledge (e.g. type/scope, scale and quality of existing surveillance tools) needed to design and use intervention monitoring tools to measure impacts of the developed interventions in the first Asian city (in phase 2), which in turn will generate practical lessons to optimise the design and application of the monitoring tools in SEA cities in phase 3. Outcomes of the proposed study will underpin future applications to larger-scale funding mechanisms (e.g. the newly established MRC Applied Global Health Research Board) to complete the subsequent study phases.