Food Import Dependency, Urbanisation, and Adult Obesity Prevalence in Sub-Saharan Africa: A Longitudinal Panel Analysis of Commercial Determinants of Health

<title>Abstract</title> <p>Background Adult obesity is rising rapidly across Sub-Saharan Africa. The structural and commercial determinants of this transition remain poorly understood. Most macro-level studies use aggregate trade openness indicators that do not capture food-system change, and the role of urbanisation in modifying food import effects on obesity has not been tested longitudinally in the region. This study is among the first to examine food import dependency, distinct from aggregate trade openness as a longitudinal predictor of obesity across 39 Sub-Saharan African nations over 23 years, and the first to formally test urbanisation as a modifier of this association using panel methods. Methods A longitudinal ecological panel study was conducted using data from 39 Sub-Saharan African nations between 2000 and 2022, generating 1,557 country-year observations. The primary exposure was food import dependency, defined as food imports as a percentage of total merchandise imports. Adult obesity prevalence, sourced from NCD Risk Factor Collaboration estimates, was the outcome. A two-way fixed effects model with clustered HC3 standard errors served as the primary analysis. A difference generalised method of moments model was estimated as a sensitivity analysis. Results Food import dependency was positively associated with adult obesity prevalence across all specifications (fixed effects: β = 0.051, 95% CI: 0.046 to 0.056, p &lt; 0.001; difference GMM: β = 0.048, p &lt; 0.001). The coefficient was stable across estimators. Foreign direct investment showed no significant association with obesity. Urbanisation showed a marginal positive association (β = 0.005, p = 0.090). Marginal effects analysis suggested the food import effect strengthened at higher urbanisation levels, though the interaction term was not statistically significant (β = 0.002, p = 0.107). Conclusions Food import dependency was consistently associated with adult obesity prevalence across Sub-Saharan Africa. These findings are consistent with the nutrition-sensitive trade governance argument and support further investigation of food import composition as a structural lever for NCD prevention.</p>