The link between income inequality and obesity inJapanwas evaluated. Income inequality of all 47 prefectures of Japan as expressed by Gini coefficient was obtained from National Statistics Center, Japan. The rate of obesity (%) was also obtained from National NutritionSurvey,Japan. The effect of income inequality on obesity was evaluated by ecological study. Income inequality as expressed by Gini coefficient was 0.31 ± 0.01 and the rate of obesity was 31.6% ± 5.6%. Gini coefficient was significantly and positively correlated with the rate of obesity (r = 0.490, p = 0.0005). Income inequality was might be associated with the rate of obesity inJapan.
Obesity and its related diseases has become serious problem and public health challenge in Japan. For example, 30.3% in men and 21.5% in women were reported to be obesity (Body mass index ≥ 25 kg/m2) by the National Nutrition Survey in Japan [
In this study, we investigated the effect of income inequality on obesity in all 47 prefectures of Japan by ecological study.
Income inequality as expressed by Gini coefficient (2009) was obtained by National Statistics Center, Japan [
The rate of obesity in men (%) in all 47 prefectures of Japan was obtained from the National Nutrition Survey by Ministry of Health, Labour and Welfare, Japan [
A simple correlation analysis was used to test the significance of the linear relationship among continuous variables: p < 0.05 was considered to be statistically significant.
Gini coefficient was 0.31 ± 0.01, and Okinawa prefecture, which is located most southern part of Japan was the highest (0.339) and Kyoto prefecture was the lowest (0.274). The rate of obesity in men was 31.6% ± 5.6%, and Okinawa prefecture was the highest (45.2%) and Yamaguchi prefecture was the lowest (22.1%).
Income inequality expressed as Gini coefficient were significantly and positively correlated with the rate of obesity in men (%) (
We evaluated the income inequality expressed as Gini coefficient and obesity in all 47 prefectures of Japan by ecological study. Positive correlation between income inequality and obesity was noted in this study.
Chiavegatto et al. reported the difference between high and low income inequality areas was statistically significant for homicide, ischemic heat disease, HIV/AIDS and respiratory disease in Brazil [
Potential limitations still remain in this study. First, we used an ecological study. The link between income inequality expressed as Gini coefficient and the rate of obesity, which was noted in this study, may not apply for the link among individuals. Second, we could not obtain the data of the rate of obesity in women. The third, other confounding factors i.e. education, occupation, lifestyle and locations of prefectures were not evaluated in this study, therefore, we could not evaluate the link between income inequality and obesity as accurately as we wished. Further ongoing investigations are urgently required to prove such a link.