More than half a billion people, or one in 10 adults worldwide, are obese - more than double the number in 1980 - as the obesity epidemic spills over from wealthy into poorer nations, researchers said on Thursday.

And while rich nations made big strides in cutting rates of High cholesterol and hypertension, or high blood pressure, the overall number of people with high blood pressure rose from 600 million in 1980 to nearly 1 billion in 2008, fueled by an aging and expanding global population.

“Overweight and obesity, high blood pressure and High cholesterol are no longer Western problems or problems of wealthy nations,” said Majid Ezzati of Imperial College London and Harvard University, who led the studies published in the Lancet journal.

The research, conducted with the World Health Organization, benchmarks changes in key risk factors that affect heart health.

Heart disease is the No. 1 killer of people in the industrialized world, and billions of dollars are spent every year on medical devices and drugs to treat it. Thursday’s study showed progress in some areas, but also areas of major concern.

In North America, for example, there have been big advances in reducing rates of uncontrolled high blood pressure in men. In Australia, New Zealand and New Guinea, rates of hypertension in women have also improved.

GLOBAL ‘TSUNAMI’ OF HEART DISEASE

But body mass index, a key measure of obesity, has risen broadly. “The world is getting more and more overweight and obese,” Ezzati said in a telephone interview.

Being overweight or obese raises the risk of heart disease, diabetes, some cancers and arthritis. Hypertension, another key risk factor for heart disease, is the world’s biggest killer.

Obesity-related diseases account for nearly 10 percent of U.S. medical spending or an estimated $147 billion a year. In Europe, more than half of adults are overweight or obese, piling pressure on already stretched healthcare budgets.

But the studies showed that major heart risks are no longer just an affliction of wealthy, western nations.