Background At a country level, population obesity prevalence is often associated with economic affluence, reflecting a potential adverse outcome concomitant with economic growth. We estimated the pattern and strength of the empirically observed relationship between national income and adult obesity prevalence, and the moderating role of countries' macro-environments on this relationship. Methods We assembled data on national obesity prevalence, income and a range of variables that characterize macro-environments related to 147 countries from multiple international organizations and databases. We used a Bayesian hierarchical model to estimate the relationship (elasticities) between national income (using Gross Domestic Product Per Capita, GDPPC) and adult obesity prevalence, and the moderating effects of five different dimensions (globalization orientation, demographic characteristics, economic environment, labor market characteristics, and strength of health policies) of countries' macro-environments on the income elasticities. Using the latest (2019-2024) available national income growth projections from the International Monetary Fund, we forecast future global trends in obesity prevalence. Findings Over the 40-years 1975-2014, adult obesity prevalence increased at a declining rate with GDPPC across the 147 countries. The mean income elasticity estimates were 1.23 (95% credible interval 1.04-1.42) for males and 1.01 (0.82-1.18) for females. The elasticities were positively associated with the extent of political globalization and negatively associated