"And this epidemic of severe obesity is too extensive to be tackled with medications such as blood pressure-lowering drugs or diabetes treatments alone, or with a few extra bike lanes."
Ezzati said co-ordinated global steps were needed, including addressing the pricing of healthy foods versus unhealthy foods, or taxing high sugar and highly processed foods.
Yet excessively low body weight remained a serious public health issue in the world's poorest regions, the study's authors said, and rising global trends in obesity should not overshadow the problem of many people not getting enough to eat.
In South Asia, for example, almost a quarter of the population was underweight. In Central and East Africa, about 12 per cent of women and 15 per cent of men were underweight.
The study, published in the Lancet medical journal, involved the World Health Organisation and more then 700 researchers worldwide. It analysed data from nearly 20 million adults from 186 countries.
It found that during the past four decades the average age-corrected male BMI rose to 24.2 from 21.7, and in women rose to 24.4 from 22.1. That was equivalent to the world's population becoming 1.5kg heavier each decade, the researchers said.
They predicted that if the trends continued, 18 per cent of men and 21 per cent of women would be obese by 2025.
