The Wellcome-funded study, published today in The Lancet and led by Imperial College London and the World Health Organization (WHO), looked at how obesity has changed worldwide from 1975 to 2016.
It analysed weight and height measurements from nearly 130 million people aged over five – the largest, most global study to look at obesity in children and adolescents. More than 1,000 researchers contributed to the study.
Dr Sophie Hawkesworth, from Wellcome's Population Health team, says: "Global population studies on this scale are hugely important in understanding and addressing modern health challenges. This study harnessed the power of big data to highlight worrying trends of both continuing high numbers of underweight children and teenagers and a concurrent stark rise in childhood obesity."
Increase in obesity rates in children and adolescents
The study found the number of obese 5 to 19 year olds has risen from 11 million in 1975 to 124 million in 2016.
The rise in childhood and adolescent obesity in low- and middle-income countries has accelerated, especially in East Asia, Latin America and the Caribbean.
And while obesity rates among children and adolescents have begun to plateau in higher income countries, they still remain dangerously high. More than 1 in 10 young people in the UK and 1 in 5 in the USA are obese.
The authors say that if current trends continue then by 2022 more 5 to 19 year olds will be obese than will be moderately or severely underweight.
Large numbers of underweight children and adolescents remain
Despite rises in obesity, currently more children and adolescents remain underweight than obese globally. The large numbers of moderately or severely underweight young people still represents a major public health challenge, especially in the poorest parts of the world.
India has had the highest prevalence of moderately and severely underweight children and adolescents for the past four decades.
Addressing all aspects of malnutrition
Both under-nutrition and excessive weight gain are complex problems, which will require a range of solutions that target individuals but also the wider environments where people live.
Together with global health partners and the international research community, Wellcome is working to help identify new research opportunities that could help better understand all aspects of malnutrition, its long-term health consequences and the design of effective interventions.