The report also confirmed that China and the US now have the most obese people in the world, with the US having the most severely obese people of any country. China also comes second in the number of underweight men and women, after India.
The researchers said the trend of increasing obesity slowed among some countries after 2000, notably in countries with high incomes, perhaps as a result of increased concern about obesity.
According to the researchers no country has more than a 50% chance of halting the growth of obesity on current trends, and the UK's chances are between 0% and 25%.
The study authors concluded: “Some high-income and middle-income regions are now facing an epidemic of severe obesity.”
They added that rising obesity levels have not yet shown an increase in earlier deaths, but this could be due to the availability of drugs to combat high blood pressure, high cholesterol and type 2 diabetes in richer countries.
The researchers said even these drugs “will not be able to fully address the hazards of such high BMI levels” in the future, warning that “bariatric surgery [weight loss surgery] might be the most effective intervention”.
An NHS Behind the Headlines report on the study said: “The figures in the study make for startling reading. Although it's difficult to draw conclusions from a mass of data covering the whole world, it seems clear that adults are becoming progressively heavier, and high-income countries such as the US and UK now have a large proportion of adults who weigh more than is healthy.
“The study relies on hundreds of different studies carried out by different organisations, so it is subject to any inaccuracies that might have happened during the measurement and recording process.
“However, the researchers only chose studies that had independent measurements of weight and height, so the overall results should be more accurate than if they'd relied on self-reported measurements.
“We shouldn't ignore the number of people who are still underweight in the world. While this is a small proportion of people in rich countries like the UK, more than 200 million people in India are underweight for their height.
“China and India together account for more than half of the men and women who are underweight in the world. It is striking that China and India both also feature in the top 10 countries with obesity in men.
“The release of the data has been accompanied by calls from health campaigners for the government to do more to tackle unhealthy eating and obesity.”