The Conditional Effect of Income Inequality on Obesity: A Cross-National Comparative Analysis

Research on income inequality and obesity shows inconsistent results. This study tests if this relationship depends on a country's existing inequality level. We analyzed individual-level data (N = 22 938) from the 2011 and 2021 International Social Survey Programme. The sample included 10 affluent nations, divided into low-Gini and high-Gini groups. We used two-way fixed-effects linear probability models to estimate how changes in the Gini coefficient affect obesity risk. The effect of inequality on obesity is conditional. In low-Gini countries, a one-unit increase in the Gini coefficient was associated with a 2.0 percentage point higher probability of obesity (P < .01). However, we found no significant association in high-Gini countries. The health impacts of rising inequality are most severe when they disrupt established egalitarian norms. We suggest "ideological buffering" may explain the lack of effect in highly unequal societies, reflecting how profound stratification is often normalized and justified.