A Systems Science Approach to Understanding Persistent Child Undernutrition in North East Nigeria: Causal Loop Modelling and Policy Simulation

Child undernutrition in North East Nigeria reflects a complex adaptive system in which humanitarian, food system, health service, social, and political factors interact across multiple scales in ways that defy linear causal analysis. Conventional analytical frameworks have failed to account for feedback loops, non-linear dynamics, and cross-sectoral interactions that perpetuate undernutrition despite significant investment. This study applies systems science methods to understand and model the persistent drivers of child undernutrition across conflict-affected communities in Borno, Adamawa, and Yobe States. A participatory group model building process engaged 120 stakeholders including nutrition programme managers, community leaders, health workers, food system actors, and affected community members in constructing causal loop diagrams of the undernutrition system. Complementary quantitative data collection across 800 households provided empirical grounding for system variable estimation. Causal loop diagrams were translated into a system dynamics stock-and-flow model, calibrated against historical undernutrition surveillance data from the Nutrition Information Management System. Policy simulation runs tested the impact of sixteen hypothetical intervention combinations under three humanitarian context scenarios on ten-year wasting and stunting projections. Results identified high-leverage intervention points that conventional programme evaluations have missed, including community social cohesion, informal market food supply chains, and healthcare worker retention. The study produces an original methodological contribution by adapting systems science tools to humanitarian nutrition research in Nigeria, advancing the field beyond siloed programme evaluations. Keywords: systems science, child undernutrition, causal loop modelling, North East Nigeria, policy simulation.