Tenfold increase worldwide in childhood and adolescent obesity in four decades: new study

More obese children and adolescents than underweight, globally by 2022

The number of obese children and adolescents (aged five to 19 years) worldwide has risen tenfold in the past four decades, according to a new study led by Imperial College London and the World Health Organization (WHO). If current trends continue, authors say more children and adolescents will be obese than moderately or severely underweight by 2022.

The study is published in The Lancet on World Obesity Day (11 October). It analysed weight and height measurements from nearly 130 million people over five years old (31.5 million people aged five to 19, and 97.4 million aged 20 and older), the largest number of participants ever involved in an epidemiological study.

Dr. Zulfiqar Bhutta, Co-Director, SickKids Centre for Global Child Health, is one of more than 1,000 researchers who contributed to the study, which looked at body mass index (BMI) and how obesity has changed worldwide from 1975 to 2016.

During this period, obesity rates in the world’s children and adolescents increased from less than one per cent (equivalent to five million girls and six million boys) in 1975 to nearly six per cent in girls (50 million) and nearly eight per cent in boys (74 million) in 2016. Combined, the number of obese five to 19 year olds rose more than tenfold globally, from 11 million in 1975 to 124 million in 2016. An additional 213 million were overweight in 2016 but fell below the threshold for obesity.

"The rapid rise in the double burden of childhood and adolescent obesity poses one of the greatest public health challenges of the 21^st century. Tackling this through effective preventive strategies is critical to achieving the sustainable development goal targets of improving health and reducing the burden of non-communicable diseases," says Bhutta.

The authors say that if post-2000 trends continue, global levels of child and adolescent obesity will surpass those for moderately and severely underweight for the same age group by 2022.

Nevertheless, the large number of moderately or severely underweight children and adolescents in 2016 (75 million girls and 117 million boys) still represents a major public health challenge, especially in the poorest parts of the world. This reflects the threat posed by malnutrition in all its forms, with there being underweight and overweight young people living in the same communities.  

Children and adolescents have rapidly transitioned from mostly underweight to mostly overweight in many middle-income countries, including in East Asia, Latin America and the Caribbean. The authors say this could reflect an increase in the consumption of energy-dense foods, especially highly processed carbohydrates, which lead to weight gain and poor lifelong health outcomes.

In 2016, there were 50 million girls and 74 million boys with obesity in the world, while the global number of moderately or severely underweight girls and boys was 75 million and 117 million respectively.

The number of obese adults increased from 100 million in 1975 (69 million women, 31 million men) to 671 million in 2016 (390 million women, 281 million men). Another 1.3 billion adults were overweight, but fell below the threshold for obesity.

In conjunction with the release on the new obesity estimates, WHO published a summary of the Ending Childhood Obesity (ECHO) Implementation Plan. The plan gives countries clear guidance on effective actions to curb childhood and adolescent obesity. WHO has also released guidelines calling on frontline healthcare workers to actively identify and manage children who are overweight or obese.