Wider income gaps, wider waistbands? An ecological study of obesity and income inequality

Abstract

Objectives: To see if obesity, deaths from diabetes, and daily calorie intake are associated with income inequality among developed countries. Design: Ecological study of 21 developed countries. Countries: Countries were eligible for inclusion if they were among the top 50 countries with the highest gross national income per capita by purchasing power parity in 2002, had a population over 3 million, and had available data on income inequality and outcome measures. Main outcome measures: Percentage of obese (body mass index >30) adult men and women, diabetes mortality rates, and calorie consumption per capita per day. Results: Adjusting for gross national per capita income, income inequality was positively correlated with the percentage of obese men ( r = 0.48, p = 0.03), the percentage of obese women ( r = 0.62, p = 0.003), diabetes mortality rates per 1 million people ( r = 0.46, p = 0.04), and average calories per capita per day ( r = 0.50, p = 0.02). Correlations were stronger if analyses were weighted for population size. The effect of income inequality on female obesity was independent of average calorie intake. Conclusions: Obesity, diabetes mortality, and calorie consumption were associated with income inequality in developed countries. Increased nutritional problems may be a consequence of the psychosocial impact of living in a more hierarchical society.