Yet the prevalence of childhood obesity appears to vary across countries.
The study estimated that in 1975, there were 11 million children 5 to 19 with obesity, and that number increased to 124 million in 2016.
Where childhood obesity is most and least prevalent
The highest prevalence of obesity in children 5 to 9 is in the Pacific Islands, at around 30% for both boys and girls, said Juana Willumsen, an expert in WHO’s Department of the Prevention of Noncommunicable Diseases.
Among children 5 to 9, Nauru appeared to have the highest obesity rate at 36.3% in 2016, according to WHO data.
Based on that 2016 data, Nauru is followed by the Cook Islands at 36.1%, Palau at 35.5%, Niue at 33.3%, the Marshall Islands at 31.2%, Tuvalu at 31.1%, Tonga at 30.2%, Kiribati at 27.5%, Micronesia at 25.2% and Samoa at 24.9%.
Among children 10 to 19, Nauru still appears to have the highest obesity rate at 31.7%, followed by the Cook Islands at 30.3%, Palau at 29.4%, Niue at 27.6%, Tuvalu at 25.3%, Tonga at 24.9% and the Marshall Islands at 24.4%, according to WHO data from 2016.
“However, these are small countries,” Willumsen wrote in an email. “The next highest is Kuwait.” That Middle East country appears to have an obesity rate of 23.1% among children 5 to 9 and 22.8% among children 10 to 19, based on that WHO data from 2016.
On the other hand, “a number of countries have childhood obesity prevalence below 1% for boys,” Willumsen said, including Uganda and Rwanda among ages 5 to 9 and Niger, Burkina Faso and Ethiopia among ages 10 to 19, based on WHO data from 2016.
Several countries also have childhood obesity rates below 2% for girls, Willumsen said, including Cambodia and Burkina Faso among ages 5 to 19, according to 2016 data.
Denmark, France, Ireland, Latvia and Norway were among the countries with the lowest rates, ranging from 5% to 9% in either boys or girls, according to WHO. Those findings were based on 2015-17 data among children ages 6 to 9 from the WHO Childhood Obesity Surveillance Initiative.
‘The definition of obesity for children is not universal’
“The definition of obesity for children is not universal like the adults’,” Barreira said.
Also, “global data is a little problematic because the methods to collect data — self-reported or measured — and to analyze data differ. So some of the information that we have is not identical depending on who is reporting,” he said. “For children — depending on who is reporting — the World Health Organization has a standard, the CDC has another standard, so obesity rates vary.”
Overall, most health groups agree that there are several risk factors for childhood obesity, including eating high-calorie and low-nutrient foods and beverages; not getting enough exercise; sitting too much, such as watching television or other screen devices; medication use; and getting inadequate sleep.
Where a child lives can influence some of those risk factors, but overall, the link between risk factors and obesity has been well-established, Barreira said.
“The main thing that we found was that there was a relationship between physical activity level — especially moderate to vigorous physical activity — and obesity in all those different places,” said Barreira, who was involved in the study. “So that relationship exists everywhere.”