Comparison of long-term changes in teenage body mass index between urban and other areas in Japan from 1986 to 2003

Japanese prefecture level panel data for the period 1986–2003 was used to analyze and compare the determinants of teenage body mass index (BMI) by sex and geographical area. Major findings through random effects estimation were as follows: (1) BMI consistently increased during the period in males aged 10–16 and in females aged 10–13 years, but not in 16-year-old females; (2) there was no difference in this trend between urban and other areas in most cases. However, the BMI of 16-year-old females was markedly lower in urban areas than in other areas. These findings suggest that girls who reach adolescence have a greater incentive to go on a diet and this tendency is more distinct in urban areas than in other areas.