Unlike the universally accepted definition of adult obesity there is more variation in how ‘overweight’ and ‘obesity’ are defined in children. As childhood is a time of development, the body mass index (BMI) is not a static measurement. However, age- and genderspecific BMI centile charts, adjusted for growth, have been designed by the Child Growth Foundation.

The charts are available to order from Harlow printing Ltd. via the website http://www.healthforallchildren.co.uk/

The SIGN guidelines for the management of obesity in children and young adults have recommended to apply the charts for both clinical and research purposes. For clinical use, obese children are defined as those with a BMI >98th centile of the UK 1990 reference chart for age and sex. Overweight children are those with a BMI >91st centile of the reference chart.²

Waist circumference centile charts for British children and adolescents have also been published.^₃ The combination of BMI with waist circumference measurement provides a more accurate assessment of adiposity. One paper, examining secular trends in waist circumference in British children, showed that waist circumference increased sharply among 11–16-year-olds between the years 1987–1997, indicating that abdominal obesity has increased much faster than overall BMI.⁴ It is recommended that waist circumference be recorded routinely in British schoolchildren.