0720 GMT October 18, 2017
The two-year study into childhood BMI revealed the number of obese boys had increased from six million to 74 million between 1975 and 2016, with the number of girls increasing from five million to fifty million, itv.com reported.
The biggest rise has been witnessed in the developing world; in the US and Europe rates of obesity have remained steady, the report said.
However, campaigners warned the NHS still spends £5.1 billion a year on obesity-related conditions.
Published on Wednesday in the Lancet Medical Journal, the study calls for greater government action to limit high-calorie products that appeal to children.
The study suggested a tax on sugary drinks, similar to a UK tax that's due to become law next year, as well as front-of-package labelling listing the product’s contents, and the banning of unhealthy foods by schools.
Charities said that junk food brands spend £148 million every year marketing their unhealthy products in the UK.
Caroline Cerny, from the Obesity Health Alliance, said: "Junk food companies are spending tens of millions of pounds a year on promoting their products. Government healthy eating campaigns can't possibly compete."
WHO member Fiona Bull, one of the authors of the report, called for, ‘more action and more widespread action’.
"We are surrounded by environments which market unhealthy, high fat, high sugar, high calorie food,” she said.
“That's what's on the TV, that's what's promoted at bus stops, and that's what children are seeing all day, every day.”
The report, published as part of World Obesity Day, compiled data from 31.5 million children around the globe.
Though obesity rates among Briton had plateaued, Dr. James Bentham, a member of the international team from the University of Kent, said that should not be ‘an excuse for complacency’.
"More than one in five young people in the USA and one in 10 in the UK are obese," he said.
British girls have the sixth highest obesity rate in Europe (73rd globally), according to the study, while boys were 18th in Europe (84th globally). However, British obesity rates have tripled in the last four decades.
Dr. Harry Rutter from the London School of Hygiene and Tropical Medicine said childhood obesity is a ‘huge crisis’ in Britain, particularly in poorer areas.
Noting that obesity levels for affluent children had fallen over the past decade, while rates had risen for the poorest, Rutter said: “We don't only have inequality, we have widening inequality, and we're not getting any better at dealing with it."
Tam Fry from the National Obesity Forum said the growing disparity between rich and poor undercuts claims that British obesity rates had leveled off.
"Don't be fooled by a report which initially would have you believe that child obesity levels have plateaued in the UK,” he said.
"The cost of obesity to the country should make Treasury and health ministers' hair stand on end and frighten them into action.
"What we have failed to do is to properly address obesity which is a great disgrace a great scandal."
A government spokesman said: "Current advertising restrictions in the UK on junk food are among the toughest in the world, including a ban on advertising junk food in children's media.
"We are absolutely committed to tackling childhood obesity and supporting people to make healthy choices."