Inequality in body mass indices across countries: Evidence from convergence tests

Abstract

This study examines the long-term inequality in body mass index (BMI) based on convergence tests applied to a database of 172 countries recently published by the NCD Risk Factor Collaboration. First, we find that countries converge in clubs, which indicates that country disparities in BMIs will persist over time. Second, there are three and six convergence clubs in BMIs for female and male individuals, respectively. That is, we would not observe a single convergence pattern in body weights as the nutrition transition theory and the dietary convergence hypothesis seem to suggest. Females have only one healthy club (18.5 ≤ BMI < 25) and two overweight clubs (BMI ≥ 25). Males have three healthy clubs and three overweight clubs. Third, the analysis of club convergence indicates that BMI inequality has increased due to the BMI growth observed in club 1 (the one with the highest average BMI and led by the US) in each gender group. Finally, potential determinants of BMI such as globalization, human capital, income, and urbanization are relevant to understand differences across clubs. We interpret the club convergence as the result of a heterogeneous integration of countries into the global economy, which is probably related to strong domestic preferences, policies designed to manage the impacts of globalization, and shifts in productive structures.