Because obese children tend to carry the problem into adulthood, Thomas and other doctors say those affected now will tend to be sicker as they get older, suffering from heart disease, stroke and other ailments related to being overweight.

In North and South America, it is estimated that just under half of the region's children will be overweight by 2010, up from about 28 percent. In EU countries, about 38 percent of all children will be overweight should present trends continue -- up from about 25 percent in recent surveys, according to a report published by the International Journal of Pediatric Obesity.

"We have truly a global epidemic which appears to be affecting most countries in the world," said Dr. Philip James, the chairman of the International Obesity Task Force and the author of an editorial in the journal warning of the trend.

Increasing Availability of Junk Food

Rates of overweight children are expected to rise significantly in the Middle East and Latin America as well as in Southeast Asia and the west Pacific. Mexico, Chile, Brazil and Egypt have rates comparable to the fully industrialized countries in the world, James said.

Researchers analyzed reports from 1980 to 2005 as well as World Health Organization data. They found data for trends over time covering school-age populations in 25 countries and preschool-age children in 42 countries.

Researchers concluded that the prevalence of childhood overweight increased in almost all the countries for which data were available -- a trend fueled by the increasing availability of junk food, more sedentary lives and range of other factors.

The study also detected sharp increases in obese or severely overweight children. The study forecast that the proportion of children afflicted will nearly double in Europe and the Middle East by the end of the decade. In the Americas, that figure will hit 15.2 percent, up from just under 10 percent.

Problem Carries Into Adulthood

The public health consequences of the trend alarm experts, said Dr. Phillip Thomas, a surgeon unconnected to the study who works extensively with obese patients in the northwestern English city of Manchester.

Because obese children tend to carry the problem into adulthood, Thomas and other doctors say those affected now will tend to be sicker as they get older, suffering from heart disease, stroke and other ailments related to being overweight.

"This is going to be the first generation that's going to have a lower life expectancy than their parents," Thomas said. "It's like the plague is in town and no one is interested."

Another doctor who examined the journal report was Dr. Brian McCrindle, a childhood obesity expert and professor of pediatrics with the hospital for sick children in Toronto, Canada. He warned that the looming problem must be addressed.

"The wave of heart disease and stroke could totally swamp the public healthcare system," he said.

He warned that lawmakers had to take a broader view of the looming problem -- and consider doing things such as banning transfats and legislating against direct advertising of junk food toward children.

"It's not going to be enough any more just to say to the consumer you have to change to your behavior," he said.