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

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, fuelled by an ageing 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.

"When you put aside two or three countries -- the U.S., Australia and New Zealand -- it's a lot more middle income countries where obesity is the highest," Ezzati said.

Average levels of total blood cholesterol fell in North America, Australia, New Zealand, New Guinea, and Europe, but increased in East and Southeast Asia and the Pacific region, the studies found.

Blood pressure levels are highest in the Baltic countries, and in East and West Africa.

Commenting on the findings in the Lancet, Sonia Anand and Salim Yusuf from McMaster University in Canada said they showed a global "tsunami of cardiovascular disease" which needed to be met with population-wide efforts to cut intake of bad fats and salt, and increased levels of exercise.

Ezzati said it was "heartening" that many countries had successfully reduced blood pressure and cholesterol despite rising levels of BMI, and said steps to get people to eat less salt and healthier, unsaturated fats, had helped -- as well as improved screening and treatment.

These lessons should be implemented more widely in nations of all levels of economic development, he said.

A special meeting of the United Nations General Assembly is scheduled for September to talk about the rising threat of so-called non-communicable, or chronic, diseases like heart disease, cancer and diabetes, particularly in poorer countries.