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

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.