The NHS has revealed that over a third of children aged 10 and 11 are overweight or obese when they leave primary school.
In contrast, the number of overweight children starting school is lower now than it was in 2006. Health experts are blaming weight-gain during the school years on unhealthy school dinners and bad eating habits.
The report by the NHS Information Centre looked at the measurements from over one million school children in the UK. It was found that younger boys aged four and five are more overweight than girls, with 23.9% of them topping the scales, compared to 21.3% of girls.
The problem increases as the children get older, with 34.9% of 10 and 11-year-old boys being obese compared to 31.8% of girls.
"What is needed is nothing short of a revolution and yet the government is really struggling with the basics," says Shadow Public Health Minister, Diane Abbott.
"More than one million children in England are measured as part of the National Child Measurement Programme, which shows today that while the proportion of four to five year olds who are obese has fallen, the opposite has happened among 10 and 11-year-olds," warned Tim Straughan, Chief Executive of the NHS Information Centre.
"This means that while fewer than one in 10 children in Reception Year are obese; for children in their final year of primary school this prevalence is nearly one in every five."