London ? 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.

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.

In 1980, about 5 percent of men and 8 percent of women worldwide were obese. By 2008, the rates were nearly 10 percent for men and 14 percent 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 today in the medical journal, Lancet.

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.