Obesity rates have doubled worldwide since 1980, according to new research published in the journal The Lancet.
In 1980, 4.8 percent of men and 7.9 percent of women were obese. Those percentages jumped to 9.8 percent of men and 13.8 percent of women in 2008.
However, over that same time period, there have also been some positive changes: Wealthy western nations have shown a big decline in the number of people with uncontrolled high blood pressure and high cholesterol.
While the number of people with high blood pressure and high cholesterol also declined in other parts of the world, it was only a slight drop.
"Our results show that overweight and obesity, high blood pressure and high cholesterol are no longer Western problems or problems of wealthy nations," said Majid Ezzati, the study's lead author who also is affiliated with the School of Public Health at Imperial College London. "Their presence has shifted towards low- and middle-income countries, making them global problems."
Global health experts say the increase in obesity and accompanying decline in blood pressure and cholesterol levels reflects the reality that hypertension and high cholesterol can be treated with medication, while battling obesity remains a serious worldwide challenge.
"Research is undoubtedly needed into the ... causes of the recorded trends," the authors wrote.
"We need to identify, implement, and rigorously evaluate policy interventions aimed at reversing the trends, or limiting their harmful effects, the World Health Organization's Gretchen Stevens, who is also a co-author, said in a press release. The World Health Organization provided some of the funding for the study.
Obesity is associated with numerous other serious health problems, including cardiovascular disease, diabetes and certain cancers. It's estimated that obesity-related illnesses cause 3 million deaths every year around the world. It's also at least partially responsible for skyrocketing health costs. For these reasons, the study's authors say it's urgent to address the growing obesity pandemic.
While the exact reasons for increased global obesity were still undetermined, experts said changing habits were likely contributors. Diets are different than they were 30 years ago, and modern technology has decreased physical activity. Developing countries now have a lot of the conveniences that are commonplace in wealthier nations.
"They are simply catching up with us in terms of all the modern 'conveniences,' such as fast food, vending machines and so on," said Dr. David Katz, director of the Yale University Prevention Research Center.
"We are increasingly dependent upon automobiles rather than public transit, walking, et cetera.," said Dr. Peter Muennig, assistant professor of health policy and management at Columbia University's Mailman School of Public Health in New York. "There is also a trend toward eating high-calorie processed foods, movements towards automating many manual labor jobs and working more hours at sedentary jobs."
"With globalization, there's been increased availability of Western diets that have more prepared foods, fats and certain carbohydrates," said Jeffrey Sturchio, president and chief executive officer of the Global Health Council, an alliance of organizations, health care professionals and institutions devoted to improving health worldwide. "Fresh fruits and vegetables may not be available in developing countries and lower-income neighborhoods -- even in the U.S. it may be easier to find potato chips than healthier alternatives like apples, oranges and bananas."
Sturchio said that blood pressure and cholesterol medications are difficult to get in developing countries, also contributing to the rise in obesity.
"In developing countries, there is less access to these medications, so obesity may be increasing in regions that had been characterized by normal weight. Countries that have experienced conflict or natural disaster may rely on prepared foods that often contain high levels of salt, which contributes to high blood pressure," he said.
Changing views of obesity could also be contributing to the pandemic while also reducing high blood pressure and cholesterol levels.
"Others believe that social stigma is driving the obesity-related pathology," said Muennig. "As more people become obese, the logic goes, the more comfortable people feel in their own skin, and the less stressed they feel. Stress has been strongly linked to high blood pressure and cholesterol."
In an accompanying editorial, Salim Yusuf and Dr. Sonia S. Anand of McMaster University in Hamilton, Ontario, Canada say strategies to reduce obesity will likely take decades to work.
Other experts say getting rid of subsidies offered for production of certain foods, taxing certain foods and making it more difficult to purchase unhealthy foods with government aid are policies that could work.
They acknowledge, though, that these strategies would be difficult to put into practice.
"In this country some people may not want the government to interfere with individual choice by taxing certain unhealthy foods," said Sturchio. "In developing countries weak health systems pose a significant challenge. This includes everything from healthcare worker shortages to access to care and treatment."
While new strategies are needed, some say stemming the rising tide of obesity could be as simple as returning to very old habits.
"We need to restore some of what used to be the norm in terms of foods direct from nature and daily exertion," said Katz.