The percentage of children aged 10 and 11 who are overweight or obese has risen from 31.6% in 2006/7 to 33.4% in 2010/11, according to NHS figures.
Tim Straughan, chief executive of the NHS Information Centre, said: “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 4- to 5-year-olds who are obese has fallen, the opposite has happened among 10- and 11-year-olds.
“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.”
Boys were bigger than girls in both age groups, with 23.9% of boys obese or overweight at age 4 and 5, compared with 21.3% of girls. At age 10 and 11, 34.9% of boys were obese or overweight compared with 31.8% of girls.
Experts are concerned that not nearly enough is being done to address this epidemic.
“The solution is simple — there is a real need to eat less junk food and increase physical activity,” obesity expert Tam Fry told The Sun.
“Every primary school child should have one hour of exercise as part of their lessons every day. And school food standards must not be allowed to fall.”