Almost a quarter of the world's population will be obese by 2045, according to a new study.
If current trends continue, 22.4% of people globally will be classed as obese, up from 14% in 2017, while one in eight will have type 2 diabetes, the projections show.
The researchers, from the US, Denmark and the UK, warn efforts to tackle obesity must be "significantly intensified" to stabilise the growing problem.
Their findings will be presented at the European Congress on Obesity in Vienna, Austria.
Their projections, based on analysis of population data from a World Health Organization database, suggest prevalence of diabetes globally will increase from 9.1% to 11.7% by 2045.
More than half (55%) of the US population will be obese by 2045 if trends continue, the researchers said.
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Dr Alan Moses, of Novo Nordisk Research and Development in Denmark, who will present the study, said: "These numbers underline the staggering challenge the world will face in the future in terms of numbers of people who are obese, or have type 2 diabetes, or both.
"As well as the medical challenges these people will face, the costs to countries' health systems will be enormous.
"The global prevalence of obesity and diabetes is projected to increase dramatically unless prevention of obesity is significantly intensified.
"Developing effective global programmes to reduce obesity offer the best opportunity to slow or stabilise the unsustainable prevalence of diabetes."
The authors suggest that to stop rates of type 2 diabetes going above 10% in 2045, obesity levels must fall from 14% to 10% in the same period.