A government bill to reduce childhood obesity emphasis physical activity in schools, but has been criticised for not addressing junk food advertising / Getty

Over 1.6 million children began schools overweight in the past decade, leading to concerns over future costs to the health care sector

The majority of boys from poorer backgrounds are expected to be dangerously overweight within the next couple of years, researchers have warned.

Three in five boys from the most deprived backgrounds aged between five and 11 will be overweight or obese by the year 2020, according to the UK Health Forum for the Obesity Health Alliance.

Meanwhile, obesity among boys from more affluent families is expected to fall to one in six within that time, prompting concerns over a growing class divide for health.

Levels of obesity are set to remain the same among girls however – around one in five of those aged five to 11 - regardless of background. 

The report follows calculations published by Cancer Research UK that more than 1.6 million children starting school within the past decade were overweight or obese.

The charity warned that 1,654,894 children beginning school in England between the 2006-07 and 2014-15 academic years started Year 7 at an unhealthy weight.

“These shocking figures are yet another wake-up call to the devastating impact that obesity is having on our children, with certain sections of society being harder hit than others, just as we have seen with smoking,” said Sarah Toule, head of health information at the World Cancer Research Fund.

You do not have access to view this Atom.

The “worrying” number of overweight children foretells a generation of future health problems, costing the NHS billions, Cancer Research experts added.  

Charity leaders have called on the government to improve its progress with new measures set out in a Child Obesity plan set out this year. 

The plan aims to reduce England’s rate of obesity within the next ten years, but has been criticised by doctors and health researchers for not placing enough emphasis on the dangers of junk food advertising.

Obese children are around five times more likely to become obese adults, official figures show.  

Today nearly a third of children aged two to 15 are overweight or obese, with younger generations becoming obese at earlier ages than before.

Alison Cox, Cancer Research UK’s director of prevention, said: “It’s concerning to know that so many children start secondary school – formative years in a child’s life – carrying too much weight.

“We must give children the best chance for a healthy future. Measures like the sugary drinks tax can make a difference and the Government must press ahead with this vital measure.”

“But there is no silver bullet and more action is needed. The Government has already recognised the influence of junk food marketing on children’s health by banning junk food advertising during children’s programmes - it’s time to close the loop hole during family viewing time.”