Worldwide rates of obesity have nearly doubled since 1980, but rich Western nations have made good progress in lowering hypertension and cholesterol, according to a large study of key heart disease risk factors.

Here are some key facts and the main findings of the research, which was published in The Lancet medical journal.

BODY MASS INDEX (BMI)

* BMI is measured as weight in kilograms divided by height in meters squared, or by dividing weight in pounds by height in inches squared and multiplying by 703. A person 5 feet 5 inches tall is classified as overweight at 150 pounds (68 kg) and obese at 180 pounds (82 kg).

* Being overweight or obese raises the risk of heart disease, diabetes, some cancers, arthritis and other conditions.

FINDINGS:

- In 2008, 9.8 percent of men and 13.8 percent of women in the world were obese (with a BMI above 30), compared with 4.8 percent for men and 7.9 percent for women in 1980.

- Pacific island nations have the highest average BMI in the world, reaching 34-35, up to 70 percent higher than some countries in Southeast Asia and sub-Saharan Africa.

- Among high-income countries, the United States has the single-highest BMI (over 28 for both men and women), followed by New Zealand. Japan has the lowest BMI (22 for women and 24 for men), followed by Singapore.

- Among high-income countries, between 1980 and 2008, BMI rose most in the United States (by more than 1 point per decade), followed by New Zealand and Australia for women and followed by the UK and Australia for men. Women in a few Western European countries had virtually no rise in BMI.

- The UK has the sixth-highest BMI in Europe for women and ninth-highest for men (both around 27). Turkish women and Czech men have the highest BMI in Europe (both around 28). Swiss women had the lowest BMI in Europe (around 24).