The global financial crisis caused a surge in unhealthy eating as people switched to cheaper, higher calorie foods, according to a new report from the Organisation for Economic Cooperation and Development. As a result, rising poverty likely contributed to rising obesity in several developed countries, including Canada, France, and Switzerland.

“The economic crisis may have contributed to a further growth in obesity, but most governments need to do more to stop this rising tide,” said Michelle Cecchini, a health expert with the OECD, which promotes economic progress in 34 mostly developed countries. The report, released Tuesday, shows that the majority of people living in those countries is overweight or obese.

Some people are more likely to be obese than others, with women and the poor most vulnerable. Between 2007-2009 in the United States, fruit and vegetable consumption decreased as unemployment increased. People in the UK, between 2008-2009, spent 8.5 percent less on food but consumed 4.5 percent more calories. One 2013 study in Australia showed people in financial distress were 20 percent more likely to become obese than those who aren't.

The United States remains "the fattest country in the OECD," they said. Before 1980, fewer than 45 percent of Americans were overweight. Now more than two-thirds of American adults is overweight, including one-third who are obese. (A body mass index of 30 or greater is considered obese; 25 or greater is overweight.)

While rates in the U.S. are the highest, they have not lately been rising, the report said. The rate of increase has slowed globally and stabilized in countries other than the U.S., including Italy and the United Kingdom. The World Health Organization estimated in 2008 that more than 1.4 billion adults were overweight.

The cost of the problem isn't only in terms of the health and quality of life of citizens. In the United States, between five percent and 10 percent of health expenditures are for obesity, according to the report, and those costs "will rise rapidly in the coming years as obesity-related diseases set in." These include heart disease, diabetes and arthritis.

The OECD says governments should enact more comprehensive policies to curb the epidemic. It praised Mexico for a 2013 campaign to raise awareness about nutrition and health care. Mexico, like other countries, passed a junk food tax raising the price of sugery drinks. A similar measure in New York City failed. The OECD cautions that these programs must be "carefully designed to achieve their intended effects."

"Several countries have developed multi-stakeholder frameworks, involving business and civil society actors in the development of public health policies," the authors wrote. "Evaluations of the effectiveness of these initiatives are only beginning to emerge."