FRIDAY, Feb. 4 (HealthDay News) -- New research shows that obesity is on the rise worldwide -- it's doubled since 1980 -- but people in the wealthiest nations are managing to reduce their blood pressure and cholesterol levels.

The mixed picture, courtesy of three studies published online Feb. 3 in The Lancet, suggests that medicine may be helping those in Western countries fend off some of the physical effects of weighing too much. Still, obesity remains a huge problem, particularly outside Southeast Asia and sub-Saharan Africa.

In 2008, almost 10 percent of men and 14 percent of women in the world were estimated to be obese. That's up from 5 percent and 8 percent, respectively, in 1980.

The average body mass index -- a measurement that takes into account a person's height and weight -- was pegged at 34 to 35 in some island nations in the Pacific. People with a BMI higher than 30 are considered to be obese.

The United States reached the highest level among wealthy countries with an average BMI of 28, putting its residents in the overweight range. New Zealand and Australia also had notably overweight people on average, while women in Turkey and men in the Czech Republic had the highest average BMIs in Europe.

Blood pressure levels were found to be lowest in South Korea, Cambodia, Australia, Canada and the United States, and highest in Portugal, Finland and Norway. Countries in Africa and the Baltic region also had high average blood pressure levels.

Cholesterol levels were highest in some Western European countries (such as Greenland, Iceland and Germany) and lowest in Africa. Among wealthier Western countries, cholesterol rates were lowest in the United States, Canada, Greece and Sweden.

"It's heartening that many countries have successfully reduced blood pressure and cholesterol despite rising BMI," Majid Ezzati, senior author of the obesity study and a professor at Imperial College London, said in a journal news release. "Improved screening and treatment probably helped to lower these risk factors in high-income countries, as did using less salt and healthier, unsaturated fats."

The ultimate effect of the rise in obesity should be higher levels of diabetes, although medications and other medical treatments may dampen the increase, Dr. Lawrence J. Cheskin, director of the Johns Hopkins Weight Management Center at Johns Hopkins Bloomberg School of Public Health, explained in an interview.

"Don't assume there's little we can do as individuals and nations. We are not getting heavier because our genes are changing," Cheskin said. "Let's work on changing our food supply and environment, reducing poverty, enhancing education about health promotion, and keeping moving."

More information

For more about obesity, visit the U.S. National Library of Medicine.