There are now more overweight people across the world than hungry ones, according to experts.
The number of people overweight has topped 1bn across the world
US professor Barry Popkin said all countries - both rich and poor - had failed to address the obesity boom.
He told the International Association of Agricultural Economists the number of overweight people had topped 1bn, compared with 800m undernourished.
Speaking at an Australian conference, he said changing diets and people doing less physical exercise was the cause.
Professor Popkin, from the University of North Carolina, said that the change had happened quickly as obesity was rapidly spreading, while hunger was slowly declining among the world's 6.5bn population.
He told the conference at the Gold Coast convention centre near Brisbane: "Obesity is the norm globally and under nutrition, while still important in a few countries and in targeted populations in many others, is no longer the dominant disease."
He said the "burden of obesity", with its related illnesses, was also shifting from the rich to the poor, not only in urban but in rural areas around the world.
China typified the changes, with a major shift in diet from cereals to animal products and vegetable oils accompanied by a decline in physical work, more motorised transport and more television viewing, he added.
And he urged governments to begin to develop better strategies to combat the problem.
He said food prices could be used to manipulate people's diets and tilt them towards healthier options.
"For instance, if we charge money for every calorie of soft drink and fruit drink that was consumed, people would consume less of it. "If we subsidise fruit and vegetable production, people would consume more of it and we would have a healthier diet."
And University of Minnesota's Professor Benjamin Senauer, who has compared lifestyles in the US, which has high obesity rates with Japan, which has low rates, agreed.
"The average Japanese household spends almost a quarter of its income on food compared to under 14% in the US."
While a direct tax on food in the US to reduce obesity would not be politically acceptable, agricultural subsidies which resulted in cheap food could be reduced, he added.
But he said other factors, such as exercise, also played an important role.
"Japanese cities are based on efficient public transport and walking. The average American commutes to work, drives to the supermarket and does as little walking as possible."
Professor Tony Barnett, head of the diabetes and obesity group at Birmingham University, said: "It is becoming increasingly clear that the number of overweight outnumbers the malnourished.
"What is also clear is that this is not just happening in developed countries, the developing world also has serious problems.
"The biggest increases are being seen in parts of Asia with certain populations more susceptible than others. If we do not get to grips with this, problems associated with obesity, such as diabetes and cardiovascular disease, are going to increase rapidly."