Baseline body mass index (BMI) and 5-year change in BMI, by age group and gender. Numbers on the left axis represent body mass index (BMI). Solid squares represent the mean baseline BMI, and the error bars represent the 95% confidence interval (CI). Numbers on the right axis represent mean change in BMI. Open triangles represent the mean 5-year change in BMI, and the error bars represent the 95% CI.