Nearly one in four children are obese or overweight when they start primary school and one in three are too fat by the time they leave, according to official figures.
The new data from the government's national child measurement programme in schools showed there had been no progress since last year in reducing the numbers of overweight children and provoked calls for greater efforts to tackle the obesity epidemic in the young.
National Obesity Forum spokesman Tam Fry said: "We had high hopes that there would have been a marked improvement after all the money that is being thrown at the problem but it seems that more radical measures will be needed to reduce obesity levels."
Lisa Cooney, head of education for the World Cancer Research Fund, said: "These latest figures are a real cause for concern. This is because research has shown that the more overweight a child is, the more likely it is they will be overweight as an adult. This is important for cancer because scientists now say that, after not smoking, maintaining a healthy weight is the most important thing we can do for cancer prevention."
Four- and five-year-olds in reception class and 10- and 11-year-olds in Year 6, the last year of primary school, are weighed and measured each year. Nearly a million children were weighed this year, 88% of those eligible. The programme has been running since 2005, but this is the second year that the results have been published by the NHS Information Centre.
The report shows there was little or no significant change in 2007-08 in the proportion of children who were obese, overweight or underweight in both age groups, compared with the previous year.
Public health minister Dawn Primarolo said obesity was one of the biggest public health challenges facing the country. "If we do nothing, 90% of today's children could be overweight or obese by 2050, leaving them at risk from serious illnesses such as heart disease or diabetes."
She pointed to a programme being introduced by the government in January, called Change4Life, which is intended to galvanise communities to play their part in promoting activity and healthier eating.
