The 2008 financial crisis spurred obesity's spread in the Organisation for Economic Cooperation and Development's 34 member countries—most of whose inhabitants are overweight, an OECD report said Tuesday.
The grouping, which includes the world's richest nations, has seen obesity levels continue to rise over the past five years, albeit more slowly than before.
"One in five children is overweight, on average, in OECD countries, but rates are as high as one in three in countries like Greece, Italy, Slovenia and the United States," said a press statement.
The economic crisis was partly to blame, the OECD report said, with less spending on food overall, and a switch to cheaper, high-calorie junk alternatives.
The report noted a 5.6-percent drop in fruit and vegetable consumption for every one-percent rise in unemployment in the United States in the period 2007-09.
Obesity claims a heavy personal and financial toll in terms of diseases like diabetes, heart disease and cancer.
Severely obese people die eight to ten years earlier than those of normal weight—a similar rate to smokers.
And obesity is estimated to gobble up one to three percent of total health expenditure in most countries—as much as five to 10 percent in the United States.
The findings are to be presented Wednesday at the European Congress on Obesity in Sofia, Bulgaria.
The report said obesity rates were stable in England, Italy and the United States but have increased two to three percent in Australia, Canada, France, Mexico, Spain and Switzerland.
Obesity is defined by the World Health Organisation as a body mass index (weight in kilogrammes divided by the square of one's height in metres) of 30 and above.
The UN's health agency attributes 3.4 million adult deaths per year to being overweight or obese.
Until 1980, fewer than one in ten people in the OECD were obese, compared to 18 percent of the adult population now—one in three adults in Mexico, New Zealand and the United States and more than one in four in Australia, Canada, Chile and Hungary, said the document.
Rates in Asian countries were two to four percent among adults.