WEIGHING IN: Nine-year-old Wong Min-hin weighs 49kg at 1.38m. Obesity is becoming an ever-bigger problem in developed countries. Picture:Reuters

More than four million British children are too fat, according to an international study.

It found that four in ten youngsters aged five to 19 were medically obese or overweight.

Researchers at Imperial College London and the World Health Organisation said the total was up from 2.66million in 1975 to 4.53million last year.

The experts warned of an ‘absolute crisis’ in child health leading to heart disease, cancer and diabetes.

‘These worrying trends reflect the impact of food marketing and policies across the globe, with healthy nutritious foods too expensive for poor families and communities,’ said Majid Ezzati, the Imperial professor who led the study.

‘The trend predicts a generation of children and adolescents growing up obese. We need ways to make healthy, nutritious food more available at home and school, especially in poor families and communities, and regulations and taxes to protect children from unhealthy foods.

‘Most high-income countries have been reluctant to use taxes and industry regulations to change eating and drinking behaviours.’

The study found that 1.13million five to 19-year-olds were obese, up from 360,000 in 1975. The rate for boys was 10.9 percent and for girls 9.4 per cent.

Dr Fiona Bull of WHO said politicians had failed to act after years of warnings. ‘The response has been insufficient, inadequate,’ she added. ‘Obesity is a global health crisis today, and threatens to worsen in coming years unless we start taking drastic action.

‘We are surrounded by environments which market unhealthy, high fat, high sugar, high calorie food. That’s what on the TVs, that’s what is promoted at bus stops.

‘That’s what children are seeing all day, every day. The marketing and the promotion and the price, the specials, the two for ones, the supersizing, the scaling – these are the problems which drive overweight and obesity.’

She said the UK Government had started to take action by making plans for a sugar tax on fizzy drinks in 2018.

But she called for severe limits on marketing because firms were expanding their strategies beyond TV adverts.

Dr Alison Tedstone, chief nutritionist at Public Health England, warned that change would not happen overnight.

‘England is at the forefront of addressing childhood obesity - our sugar reduction programme and the Government’s sugar levy are world-leading but this is just the beginning of a long journey. The evidence is clear that just telling people what to do won’t work.’

The Imperial study was reported in the Lancet journal.