The number rose by 10 million over the past 25 years, the WHO said, adding that there were now more overweight and obese children in the developing world than in high-income countries.
A report for the WHO Commission on Ending Childhood Obesity (ECHO) found that almost half of overweight children under the age of five lived in Asia, while some 25 percent were in Africa.
The organization said the marketing of unhealthy food and drinks was a major contributor.
ECHO`s report notes that, in wealthier countries, poorer children are more likely to be obese, partly because of the affordability of fatty fast food and high-sugar snacks.
In poorer countries, meanwhile, the children of wealthier families are more likely to be obese, especially in cultures where "an overweight child is often considered to be healthy."
Long term disadvantage
As a result of obesity, ECHO said, many children faced obstacles in their life that would continue into adulthood.
"Overweight and obesity impact on a child`s quality of life, as they face a wide range of barriers, including physical, psychological and health consequences," Sania Nishtar, ECHO co-chair, said in a statement.
"We know that obesity can impact on educational attainment too and this, combined with the likelihood that they will remain obese into adulthood, poses major health and economic consequences for them, their families and society as a whole."
Carrot-and-stick measures
Commission co-chair Peter Gluckman told reporters that there was "an exploding nightmare in the developing world," adding that merely lecturing children about healthy diets and exercise was not enough.
Gluckman called for the use of a carrot-and-stick strategy to both incentivize and coerce food corporations to place more emphasis on healthier products.
"We have responsibilities on behalf of the world`s children to stop them from being overly obese."
WHO Director General Margaret Chan said on Sunday that "implementing the report`s recommendations will take political will and courage, as some go against the interests of powerful economic operators."
WHO report warns child obesity is `exploding nightmare`
27 January 2016
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The World Health Organization (WHO) warned on Monday that, across the globe, at least 41 million children under the age of five are obese or overweight.
