The world is becoming a heavier place, especially in the West.

Obesity rates worldwide have doubled in the last three decades even as blood pressure and cholesterol levels have dropped, according to three new studies. Researchers are concerned they don't know how much worse the obesity problem will get. (Howie McCormick/Associated Press)

People in Pacific Island nations like American Samoa are the heaviest, one of the studies shows. Among developed countries, Americans are the fattest and the Japanese are the slimmest.

"Being obese is no longer just a Western problem," said Majid Ezzati, a professor of public health at Imperial College London, one of the study's authors.

In 1980, about 5 per cent of men and 8 per cent of women worldwide were obese. By 2008, the rates were nearly 10 per cent for men and 14 per cent for women.

That means 205 million men and 297 million women weighed in as obese. Another 1.5 billion adults were overweight, according to the obesity study.

Though richer countries did a better job of keeping blood pressure and cholesterol levels under control, researchers said people nearly everywhere are piling on the pounds, except in a few places including central Africa and South Asia. The studies were published Friday in the medical journal, Lancet.

Heart disease tsunami

The research confirms earlier trends about mounting obesity and the three papers provide the most comprehensive, recent global look at body mass index, cholesterol and blood pressure. Body mass index is a measurement based on weight and height.

Experts warned the increasing numbers of obese people could lead to a "global tsunami of cardiovascular disease." Obesity is also linked to higher rates of cancer, diabetes and is estimated to cause about 3 million deaths worldwide every year.

In an accompanying commentary, Sonia Anand and Salim Yusuf of McMaster University in Hamilton, Ont. said the global forecast for heart disease was "dismal and comprises a population emergency that will cost tens of millions of preventable deaths" unless countries take quick action.

Even without the encroaching empire of Western fast food, Ezzati said waistlines are already expanding in parts of Latin America, the Middle East, and Western and Southern Africa.

Among rich countries, the U.S. had the highest average body mass Index, at 28. Rates were the lowest in Japan, ranging between 22 for women and 24 for men. Women in Belgium, France, Finland, Italy and Switzerland also stayed trim, with virtually no change in their BMI.

People with a BMI of 18-24 are considered to have a healthy weight. Those with a BMI of 25 or above are overweight and people with a BMI of 30 or more are classified as obese.

Two other studies published in the same issue surveyed blood pressure rates and cholesterol levels.

Western countries including Canada, South Korea and the U.S. had some of the lowest blood pressure rates thanks to medication, while rates are highest in Portugal, Finland and Norway.

Cholesterol levels were highest in countries like Iceland and Germany and lowest in Africa.

Ezzati said national measures like reducing salt content in prepared foods or banning trans fats could make a big dent in lowering blood pressure and cholesterol rates.

He added that it was uncertain if the world's obesity rates had peaked and predicted other health complications would soon follow. "We don't know how much worse the obesity problem will get," he said. "While we can manage blood pressure and cholesterol with medication, diabetes will be a lot harder."