The number of children suffering from obesity could be greater than official figures show, research has revealed.
Data based on body mass index (BMI) measurements may not show the true extent of the childhood obesity epidemic, according to a study by Leeds Metropolitan University.
Hundreds of children, who were not classed as being obese using BMI alone, were found to be overweight when experts looked at their waists.
Nearly 15,000 children at schools in Leeds took part in the three-year study comparing BMI, waist circumference and waist-to-height ratio.
The results found 429 boys (6pc) and 992 girls (15pc) were classed as overweight or obese who would not have been identified based on BMI measurement alone.
More than 2,000 11-year-old girls exceeded a waist measurement of 31.5in (80cm), the point at which women have an increased risk of developing Type 2 diabetes.
Experts said recent research showing a link between waist circumference and the risk of Type 2 diabetes meant the results were a concern.
Claire Griffiths, a senior lecturer who led the study, said: "Although the choice of BMI as a measure of obesity in children is well established, widespread use of BMI to assess fatness in children may conceal differences in body composition and central adiposity."
The study of 14,697 children was conducted with Prof Paul Gately, Dr Paul Marchant and Prof Carlton Cooke in collaboration with Leeds council.