an increasing trendP < 0.001
Overall mean BMI was lower in the health check group (0.27, 95% confidence interval 0.23 to 0.31 kg/m 2 , P < 0.001) compared to the control group, with an increasing trend in BMI over time (0.08, 0.07 to 0.09 kg/m 2 per year, P < 0.001).