The rise in childhood obesity is slowing down, but a third of kids are still too fat.
A new reports shows that the rate of obesity amongst under-10s has plateaued. But four out of ten 11 to 15 -year-olds still weigh too much.
Martin Gulliford, report author and professor of public health at Kings College London, said: "Children in their teens are very likely to become overweight or obese as adults, and from their obesity they might be at greater risk of chronic conditions such as type 2 diabetes.
"The concern therefore is that future generations may not be as healthy as previous generations."
The study, published in the Archives of Disease in Childhood, used GPs' electronic health records in England to monitor trends over 20 years.
Weight, height and body mass index (BMI) measurements for more than 370,000 children from 1994 to 2013 were analysed.
The findings show that the rate of growth of overweight and obesity levels, which was 8 per cent each year up to 2003, has slowed substantially in the past 10 years, to 0.4 per cent.
Trends were similar for both boys and girls, but differed by age group.
Overweight and obesity levels among two- to five-year-olds stayed relatively stable at 25 per cent for boys and 23 per cent for girls between 2003 and 2013.
In six- to 10-year-old girls and boys, about 30 per cent were overweight or obese during that time.
The highest figures were seen in 11- to 15-year-olds, where overweight and obesity levels ranged from about 26 per cent in 1996 to 35 per cent in 2003.
Among this group, overweight and obesity levels have continued to rise - to 37 per cent - in the past decade.
The study defined overweight as equivalent to a BMI (body mass index) at or above the 85th centile and obesity as above the 95th centile.
Dr Cornelia van Jaarsveld, from the department of primary care and public health sciences at King's College London, told the BBC there were several possible reasons for the 'recent stabilisation of childhood overweight and obesity rates'.
She said public health campaigns and initiatives could be starting to work.
But another explanation could be that a ceiling or 'saturation point' had been reached with obesity rates.
However, she said it was clear that the 11- to 15-year-olds were still a 'vulnerable and difficult group'.
Colin Michie, chair of the nutrition committee at the Royal College of Paediatrics and Child Health, said the good news was that things were not getting worse.
He said: "But it still leaves us with lots of problems, particularly among teenagers, who are not easily directed, at a sensitive time in their lives.
"It is a disappointment that even more children are overweight and obese at the end of primary school than at the beginning.
"Prevention works better in younger age groups, so we have to focus on cutting calories and encouraging a more active, healthy lifestyle in children."
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