(CNN)More than 250 million school-aged children and adolescents will be classed as obese by 2030, putting huge pressure on healthcare systems, a new report on childhood obesity warns.
There are currently 158 million obese children around the world, according to the World Obesity Federation's first Atlas of Childhood Obesity, which calculated a risk score for obesity in the coming decade for 191 countries.
The report said children in developing countries in Africa, Asia and Latin America were particularly at risk, as a result of fast changing lifestyles along with the growing popularity and aggressive marketing of junk food.
"There's a transition away from traditional diets and ways of doing things. People are expending less energy, becoming more sedentary and adopting a Western-style diet that's high in sugar, oil, starch and fat," Dr Tim Lobstein, director of policy at the WOF and one of the authors of the the report, told CNN.
The report said that no country included in the atlas would meet a target agreed to at a World Health Organization summit in 2013, which mandated that levels of childhood obesity should be no higher in 2025 than they were between 2010 and 2012. It added that four out of five countries it assessed had a less than 10% chance of doing so.
Dr. Lobstein said he had been surprised by the "extraordinary increase" in the number of obese children forecast by the report. As childhood obesity is closely associated with obesity in adulthood, it would place a huge burden on health systems given the link with chronic diseases like diabetes, he warned.
"That's a massive leap. It will flood health systems, particularly in developing countries," he said.
In the United States 26.3% of five to nine year olds and 24.2% of 10 to 19 year olds would be obese by 2030, the report said, giving the country a 17% chance of meeting the WHO 2025 target.
In absolute terms, the US is expected to have 17 million obese children by 2030, the largest number after China and India.
Pacific islands like the Cook Islands and Palau ranked high among the countries most at risk in the coming decade. Lobstein said that, in addition to less active lifestyles, island nations were more reliant on food imports, which were often highly processed and heavy on sugar and fat.
Lobstein said that governments around the world were reluctant to take on large food companies that had a vested increase in the status quo. He said that initiatives like sugar and soda taxes would have only a small impact, particularly because they were hard to enact in lower income countries, where governments were more likely to be persuaded by commercial interests.
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He added that he thought a younger generation would take a more activist stance towards obesity -- as they have done toward climate change.
"Most people don't want to have excess weight but there shouldn't be a stigma against the individual. It's a social problem not a private problem." he said.
