Despite rise, more children and adolescents remain underweight than obese globally, highlighting the need to improve food security to tackle, at the same time, under-nutrition and excessive weight gain.
Worldwide, there has been a more than ten-fold increase in the number of children and adolescents with obesity in the past four decades, increasing from 5 million girls in 1975 to 50 million in 2016, and from 6 million to 74 million boys, according to a new global analysis of trends in child and adolescent obesity in 200 countries, published in The Lancet.
Rates of child and adolescent obesity were highest (above 30%) in some islands in Polynesia, and were around 20% or higher in the USA and some countries in the Middle East and North Africa (eg Egypt, Kuwait, Qatar and Saudi Arabia) and the Caribbean (eg Bermuda and Puerto Rico). Overall, the global prevalence of child and adolescent obesity increased from 0.7% to 5.6% for girls, and from 0.9% to 7.8% for boys.
Despite the increase in child and adolescent obesity, globally more children remain moderately or severely underweight than obese, with 75 million girls moderately or severely underweight in 2016 and 117 million boys. Almost two-thirds of the world’s children and adolescents who are moderately or severely underweight lived in South Asia.
The study, led by Imperial College London (UK) and the World Health Organisation (WHO) and published ahead of World Obesity Day (11th October), brought together data from 2416 studies involving 128.9 million participants worldwide including 31.5 million children and adolescents aged 5-19 years, to estimate trends in body mass index (BMI) in 200 countries.
Excessive weight gain in childhood and adolescence is associated with a higher risk and earlier onset of chronic diseases such as type 2 diabetes, worse psychosocial and educational outcomes, and lifelong harms since weight loss is hard to achieve.
Average child and adolescent BMI remain high in many high-income countries in North America and Europe but trends have plateaued in recent years, even while average BMI among adults continues to rise. By contrast, the rise in average BMI has accelerated in many parts of Asia.
In addition to the 124 million children and adolescents classified as obese in 2016, 213 million children and adolescents were in the overweight range.
“Rates of child and adolescent obesity have increased significantly over the past four decades in most countries in the world,” says study author Dr. James Bentham, University of Kent, UK.
“While average BMI among children and adolescents has recently plateaued in Europe and North America, this is not an excuse for complacency as more than 1 in 5 young people in the USA and 1 in 10 in the UK are obese. Additionally, rates of child and adolescent obesity are accelerating in east, south and southeast Asia, and continue to increase in other low and middle-income regions.”
Professor Majid Ezzati, the study author from Imperial College London, adds: “While there have been some initiatives led by governments, communities or schools to increase awareness about childhood and adolescent obesity, most high-income countries have been reluctant to use taxes and industry regulations to change eating and drinking behaviours to tackle child obesity. Most importantly, very few policies and programmes attempt to make healthy foods such as whole grains and fresh fruits and vegetables affordable to poor families. Unaffordability of healthy food options to the poor can lead to social inequalities in obesity, and limit how much we can reduce its burden.”
The authors also note that policies to prevent childhood obesity in entire countries and communities need to be matched by improved treatments, such as behavioral therapy to change diet and exercise, screening and management of hypertension and liver problems, and in extreme cases, bariatric surgery.
Leanne Riley, study author from WHO, says: “The trends show that without serious, concerted action to address obesity, from improving diets and providing the means by which to increase physical activity, to implementing the health system measures required to address overweight and obesity in young people early on, then the health of millions of people will be needlessly placed in great jeopardy, leading to immense human and economic costs to communities.”
At the other extreme, in 2016 average BMI was lowest for both girls and boys in Ethiopia (16.8 kg/m2 for girls, 15.5 kg/m2 for boys), and was also low in Niger, Senegal, India, Bangladesh, Myanmar, and Cambodia. Underweight among children and adolescents is associated with higher risk of infectious disease, and for girls of childbearing age, is associated with adverse pregnancy outcomes including maternal mortality, delivery complications, preterm birth and slow intrauterine growth. In South Asia, 20.3% of girls and 28.6% of boys were moderately or severely underweight in 2016 (compared to 23.0% and 37.8% in 1975).
Between 1975 and 2016, the prevalence of moderate and severe underweight decreased from 9.2% to 8.4% in 2016 for girls, and from 14.8% to 12.4% for boys, meaning that the rate of increase in the prevalence of obesity in children and adolescents is greater than the rate of decline in under-nutrition. The authors say that if post-2000 trends continue, child and adolescent obesity is expected to surpass moderate and severe underweight by 2022.
While the study used an unprecedented number of data sources from most of the world’s countries, some regions (the Caribbean, Polynesia and Micronesia, central Asia and central Africa) had fewer data sources, meaning that there is more uncertainty in their estimates.