Between 1975 and 2016 the estimated number of obese boys in the world increased from six million to 74 million. An additional 213 million were overweight in 2016.
The percentage of Indian adults living with obesity is set to jump to around 10 per cent (3.1 per cent male and 6.9 per cent female) by 2025 from 7.5 per cent (2.3 per cent male and 5.2 per cent female) in 2014, the new analysis, ahead of World Obesity Day on Wednesday, revealed.
In some countries, including the Polynesian Islands, more than 30 per cent of children and teenagers were in the obese category.
The numbers of seriously overweight children are on the rise in low- and middle-income countries, and have hit a plateau in higher-income countries, says lead author Majid Ezzati of Imperial's School of Public Health.
"More recently, they have plateaued in higher-income countries, although obesity levels remain unacceptably high", he said. The European prevalence of childhood obesity continues to rise except in a few countries where it is levelling off (Denmark, France, Sweden, Switzerland).
"We are seeing persistent underweight and rising overweight at the same time", Ezzati explained.
The Lancet study also notes that despite these increases, there are still more children and adolescents who are moderately or severely underweight than are obese. The trend predicts a generation of children and adolescents growing up obese and at greater risk of diseases, like diabetes.
Deputy Head, Bridget Norman said: "I think children, no matter what age, are always thinking about their appearance and how they look but I think so long as we focus on the positive side, about healthiness, rather than the vanity side then it's ok". In adults, being underweight is defined as a BMI under 18.5. But if the current trends continue, that will reverse by 2022.
"Comprehensive responses are needed to create healthy environments that can support individuals in making healthy choices grounded on knowledge and skills related to health and nutrition". So we can't wait to deal with underweight, and then worry about overweight and obesity.
Over the past four decades, many countries underwent a "nutrition transition" as their economies grew, explained Hu. The study found that 75 million girls and 117 million boys were moderately or severely underweight.
Dr Fiona Bull from the World Health Organization called for tough action to crack down on "calorie-dense, nutrient-poor food" and promote more physical activity.
Most highly developed countries have a significant percentage of overweight children, but the same trend is accelerating in middle-income countries, especially in Southeast Asia.
Authors of the report are calling for policymakers to find ways to make healthy, nutritious food more available at home and school, especially in poorer families and communities, alongside higher taxes on unhealthy foods.
Study author Dr James Bentham, from the University of Kent, said: "This is not an excuse for complacency as more than one in five young people in the United States of America and one in 10 in the UK are obese".
Obesity comes with the risk of chronic diseases such as diabetes, while underweight children are more at risk from infectious diseases.
So what is it about the Swiss lifestyle that helps prevent children from piling on too many pounds? "By releasing (the data), we hope to generate more political action from countries".