Ezzati also advised that regulations and taxes to protect children from unhealthy foods roll out, or a future generation of children and adolescents growing up obese will be at greater risk of diseases, like diabetes.

The study predicts that if the trends continue, by 2020 the global level of child and adolescent obesity will surpass those for moderately and severely underweight youth from the same age group.

"These data highlight, remind and reinforce that overweight and obesity is a global health crisis today, and threatens to worsen in coming years unless we start taking drastic action," said Dr. Fiona Bull, program coordinator for surveillance and population-based prevention of noncommunicable diseases at the WHO.

As part of the solutions, the WHO released a summary of the Ending Childhood Obesity Implementation Plan, offering countries clear guidance to curb childhood and adolescent obesity. Topping the WHO guidance are promoting intake of healthy foods and physical activity, followed by preconception and pregnancy care, early childhood diet and physical activity, health and nutrition for school-age children, and weight management.

Particularly, countries should aim to "reduce consumption of cheap, ultra-processed, calorie dense, nutrient poor foods," as well as "the time children spend on screen-based and sedentary leisure activities by promoting greater participation in physical activity through active recreation and sports," said Dr. Bull.