A third of 10 and 11-year-olds in England are overweight or obese, rising to more than 40% in some regions, figures show.
The stark difference in obesity according to where children live is growing, with some regions having twice as high figures as others, according to a report from the Health and Social Care Information Centre (HSCIC).
While the percentage of children who are obese or overweight in reception year (ages four and five) is falling, the proportion of older children who are overweight and obese remains stubbornly high, and has increased to 33.2% in 2014/15 from 31.6% in 2006/07.
In some regions, there are particularly high numbers of overweight and obese children in Year 6, with Southwark and Newham in London having the highest proportion at 43.2%.
In Lambeth, 41.8% of children are overweight or obese, as are 41.9% in Tower Hamlets and 39.2% in Birmingham.
In Hartlepool in the north East of England, 41.6% of children aged 10 to 11 are overweight or obese.
In contrast, 26% of children in Surrey are the same.
The percentage of children in reception year who are obese or overweight has fallen to 21.9%, from 22.9% in 2006/07.
Simon Gillespie, chief executive of the British Heart Foundation, said: "Falling rates of obesity in reception age children is promising, but the fact remains that we now have more children leaving primary school overweight or obese and this is simply unacceptable.
"Without a robust plan to tackle this issue, obesity rates will not fall, putting future generations at risk of deadly conditions like heart disease, diabetes and stroke."
Today's figures also examined obesity alone, finding that across England, almost one in five (19.1%) Year 6 children were obese.
There are stark differences according to where children live, with 25% of children in Year 6 in the most deprived areas being obese compared to 11.5% in the least deprived.
Southwark had the highest recorded prevalence (27.8%).
Meanwhile, 25.9% of children in Wolverhampton are obese, as are 24% in Birmingham.
Richmond-upon-Thames had the lowest (10.5%), while in Rutland in the East Midlands, just 13.3% of children in Year 6 are obese.
In reception year, 12% of children living in the most deprived areas were obese, compared to 5.7% in the least deprived areas.
Shirley Cramer, chief executive of the Royal Society for Public Health, said: "It is encouraging that childhood obesity levels have fallen slightly in the short-term.
"However, we are still facing a situation where a third of children leave primary school either overweight or obese - more than was the case a decade ago - and where twice as many children leave primary school obese as enter it obese.
"It is also unacceptable that children living in the most deprived areas are more than twice as likely as those living in the most affluent areas to become obese, with all the health problems that entails."
The Children's Food Trust's head of research, Jo Nicholas, said: "These figures are staying stubbornly high from year to year - bringing the Government's forthcoming childhood obesity strategy into even sharper focus.
"That twice as many children living in poorer areas are obese compared with their peers in more affluent areas is a particularly worrying sign for the health of our most vulnerable children."
Eustace De Sousa, national lead for children, young people and families at Public Health England, said: "The doubling of obesity levels between ages four and 11 is deeply concerning and highlights that much more needs to be done to help children and families."