Changes in waist circumference among adolescents in England from 1977-1987 to 2005-2007.

OBJECTIVE: To assess change in abdominal obesity in adolescents in England. STUDY DESIGN: Health Survey for England (HSE), annual cross-sectional surveys of nationally representative samples in England. METHODS: This study included 1770 children aged 11-16 years in HSE 2005-2007 with valid waist circumference (WC) measurements. WC and body mass index (BMI) were expressed as standard deviation scores (z scores) against the growth references used for British children. RESULTS: Mean WC z scores were substantially higher than mean BMI z scores for both sexes: WC 1.0 [95% confidence interval (CI) 0.93-1.1], BMI 0.54 (95% CI 0.44-0.63) for boys; WC 1.3 (95% CI 1.2-1.4), BMI 0.48 (95% CI 0.40-0.56) for girls (both P < 0.001). Mean WC z score was higher for girls than boys (P < 0.001). Between 1997 and 2005-2007, WC increased for both boys (P < 0.01) and girls (P < 0.001), but BMI did not (P > 0.05). Only children in the lowest WC decile had an increase in WC z score less than +1 standard deviation compared with the 1977-1987 baseline. BMI z score increased across the top nine deciles of the BMI distribution by 0.4 (2nd-4th deciles) to 0.9 (top decile). CONCLUSIONS: WC in adolescents has increased substantially, and probably more than BMI. The whole population has become fatter.