BMI-based distributions of age, income, BMI and the levels of blood bio-indicators among four BMI categories.

Note: BMI categories are based on cutoff values for Chinese [14]–[16]: UW = underweight, NW = normal weight, OW = overweight, OB = obesity. Values are mean ± standard error. ANOVA (analysis of variance) is used to analyze differences among BMI-based categories: * = P<0.05, ** = P<0.01, and *** = P<0.001. Comparisons between groups: a = OB is significantly different from OW, NW or UW (P<0.05, P<0.005 or P<0.001, respectively); b = OB or OW is significantly different from NW or UW (P<0.05 and P<0.05, respectively). #US$1 = CN¥6.623 (31 December 2010, Bank of China), and per capita income/day in BMI-UW category is lower than that in three other BMI categories, respectively (P<0.05). Per capita income of US$0.50 per day (US$181 per year) was the Chinese rural poverty line in 2010 and before.