One in 25 pupils aged 10 and 11 is in the most obese category, up from one in 32 a decade ago, according to research by Public Health England.
The figures also reveal boys and girls from the most deprived backgrounds are more likely to be overweight or obese and that the health inequality is growing.
Dr Alison Tedstone, chief nutritionist with Public Health England, said: “We have over 22,000 children now at the end of their primary school severely obese and that increases health consequences and social risk for them as well.
“We have more takeaway outlets than we have ever had before.
“Walk down any high street and you are constantly prompted to buy and eat more and that will be affecting our children – the amount they eat and their body weight.”
Public Health England is working with the food industry to cut a fifth of sugar from everyday products by 2020.
Since April, soft drink manufacturers have been charged a tax on their highest calorie products.
The government has also recently unveiled the next phase of its childhood obesity strategy which proposes plans including mandatory calorie labelling on menus and restricting TV adverts.
But the parents of children playing at a park in Chiswick want to see more done.
Mother-of-four Claudine Dutton said: “I don’t think they are dealing with the right area.
“I think they should make healthier food cheaper.
“People say it is but it’s not.
“It’s much easier to buy a multi-pack of chocolate biscuits than fruit.”
And Ray Roger, who has three children, said the lure of advertising increases the challenge.
“They want what they see… It’s very difficult with everything being a lot of sugary cereal, a lot of adverts relating to sweets and chocolate.”
Caroline Cerny, of coalition group the Obesity Health Alliance, has described the figures as “very concerning”.
“The government has recently set out some bold plans with an ambition of halving childhood obesity by 2030, including a 9pm watershed on junk food adverts.
“We need all these measures to be fully and swiftly implemented to help ensure all children have the healthiest possible start in life.”