The world is becoming a heavier place. Obesity rates worldwide have doubled in the last three decades, even as blood pressure and cholesterol levels have dropped, according to three new studies published last week, in The Lancet. Researchers said they were concerned about how much worse the obesity problem could get. People in the Pacific Islands, like American Samoa, are the heaviest, Americans are the fattest and Japanese are the slimmest. In 1980, about 5% of men and 8% of women worldwide were obese. By 2008, the rates were nearly 10% for men and 14% for women. That means 205 million men and 297 million women were obese. An additional 1.5 billion adults were overweight. Though richer countries did a better job of keeping blood pressure and cholesterol levels under control, the researchers said that people almost everywhere were putting on weight, except in a few areas including central Africa and South Asia.