New estimates by World Obesity Federation (WOF) say that treatment of obesity could cost the world $1.2tn every year from 2025 unless some measures are taken to check the rapidly worsening epidemic.
It estimates that by 2025 there will be 2.7 billion, or a third of world population, as overweight and obese adults.
It says that while a third of men and women in the US were obese (34%) in 2014, it is expected to be 41% by 2025.
In the UK, obesity among adults will rise from 27% in 2014 to 34% by 2025. In Australia and Mexico will rise from 28% to 34% if nothing changes.
The US is to spend $4.2tn on treating obesity-related disease over the next eight years. This will be $390bn for Germany, while Brazil is to spend $251bn and the UK $237bn, in the same period, if conditions stay as they are now.