Obesity rates in the world's children and adolescents increased from less than one percent in 1975 to nearly six percent in girls and nearly eight percent in boys in 2016.
Combined, the number of obese five to 19-year-olds rose more than tenfold globally, from eleven million in 1975 to 124 million in 2016.
An additional 213 million were overweight in 2016 but fell below the threshold for obesity.
The WHO has six recommendations of policy actions for countries to tackle obesity and overweight in young children.
Fiona Bull with the WHO said, "The six areas include mass media campaigns to raise everyone's awareness on the consequences and the causes of overweight and obesity. Secondly, fiscal and regulatory interventions, upstream actions to change the obesogenic environment and make healthy choices the easier choices. This includes things like implementation of restrictions of marketing, food labeling and possible taxing on high fat, high sugar foods. A second area is school setting, making sure our children have access to healthy foods and physical activity. A third setting is in the physical activity area more broadly, looking at parks, sports, availability and safe ways to walk and cycle more often. And that will help children be more active and that helps maintain a healthy weight."
The study was published in the Lancet ahead of World Obesity Day, which is Wednesday.