Global childhood obesity rises 10-fold in 40 years

The number of obese children and teenagers across the world has increased 10-fold over the past four decades and is about to overtake the number who are underweight, according to the most extensive analysis of body weight ever undertaken, according to Financial Times.

The study, led by Imperial College London and the World Health Organization, used data on 31.5m children and adolescents worldwide to estimate trends in body mass index (BMI) from 1975 to 2016. The results are published in the Lancet. 

Over this period the number of obese girls, aged 5 to 19, rose from 5m to 50m, while the total for boys increased from 6m to 74m.

The definition of child obesity is relative and depends on age, with obese children exceeding the healthy standard by twice the amount that weight normally varies around the average. An average 7-year-old girl who is 125cm tall would have to weigh more than 31kg to be obese, for example.

The world’s highest childhood obesity levels are in the Pacific islands of Polynesia and Micronesia. Nauru has the highest prevalence for girls and the Cook Islands for boys: both above 33 per cent.

Among wealthy countries, the US has the highest obesity rates for girls and boys of about 20 per cent. Levels in most of western Europe are in the 7 per cent to 10 per cent range. 

A further 213m children are overweight but not sufficiently so to meet the WHO’s obesity criteria, which vary by age. Forty years ago, 0.8 per cent of the world’s children were obese; now the prevalence is close to 7 per cent. 

“Over the past four decades, obesity rates in children and adolescents have soared globally, and they continue to do so in low- and middle-income countries,” said Majid Ezzati of Imperial, the project leader. “More recently, they have plateaued in higher-income countries, although obesity levels remain unacceptably high here.” 

The study also looked at adult obesity, which increased from 100m people in 1975 to 671m in 2016. A further 1.3bn adults were overweight (with a BMI above 25) but below the threshold for obesity (BMI above 30). 

But the authors are most concerned about the findings about childhood obesity, because of their implications for public health many decades into the future.