The number of people in the world who are obese or overweight has topped 2.1 billion, up from 875 million in 1980, the latest figures published in the Lancet show.
And not one country is succeeding in treating it, said the research.
US, China and Russia had the highest rates and the UK was third in Western Europe, the 188-country study said.
Experts said the rise was due to the "modernisation of our world", causing "physical inactivity on all levels".
Researchers across the world were led by the Institute for Health Metrics and Evaluation (IHME) in Washington, in a study they said is the most comprehensive to date.
Scientists analysed data from surveys, such as from the World Health Organization, government websites, and reviewed "all articles" about the numbers of obese or overweight people in the world.
The study said rates of obesity were rising across the world, although the rates in developed countries remain the highest.
More than half of the world's 671 million obese people live in 10 countries, ranked in order:
Source: The Lancet
The UK has the third highest rates in Western Europe, with 67% of men and 57% of women overweight or obese, it said.
The study called for "urgent global leadership" to combat risk factors such as excessive calorie intake, inactivity, and "active promotion of food consumption by industry".
Prof Ali Mokdad, of the IHME, said no country was beating obesity as it was a relatively new problem.
"It takes a little bit of time to see success stories," he said.
The study reported more obese women than men living in developing countries.
Rates tended to be higher for women in developing countries as they were multi-tasking, looking after the family and working, said Prof Mokdad, so did not have the time to dedicate to managing their weight.
But more obese men than women lived in developed countries, said the study.
'Classical eating' loss
Prof Mokdad said rates were higher for men in developed countries because of longer commutes to work, fuelled by a move to the suburbs, and spending more time inactive, using computers, he said.
Prof Hermann Toplak, at the University of Graz, in Austria, said: "Over the past decades the modernisation of our world, with all the technology around us, has led to physical inactivity on all levels."
Inactivity caused self-control to spiral, he said.
Children and adults were not building up enough functioning muscle mass, and "classical eating" had been replaced by "uncontrolled food intake" spread over the day. he said.
Prof John Newton, chief knowledge officer at Public Health England, said poor nutrition and lack of exercise were a big risk factor in Britain's most deprived areas.
PHE ran campaigns to help families be healthy, more active, and cut down on fat and sugar, he said.
He added: "Obesity is a complex issue that requires action at national, local, family and individual level; everyone has a role to play in improving the health and well-being of the public, and children in particular."