A Nobel Prize-winning economist on Tuesday offered a theory for why more Americans apparently choose to stay fat: they are counting on medical progress to cure any ailments the extra weight might cause.

Economist Gary Becker told the annual Milken Institute Global Conference that the proliferation of cars, cheap fast food, television and computers have all contributed to the pounds gained by young Americans in the last decade.

But the reason they stay fat, he said, may have to do with their faith in science.

“People look ahead and say, ‘I hear from science about all these fabulous innovations.’ If they get a bad organ they will get it replaced,” Becker said. “There is a certain rationality in engaging in high-risk behavior on the belief there will be a cure.”

Coincidentally, the U.S. Centers for Disease Control and Prevention on Tuesday released studies showing that while Obesity is increasing in the United States, it alone may not be killing as many people as had been thought because of medical and health care advances.

Becker, a professor of economics at the University of Chicago, won a Nobel Prize in 1992 for his application of economic theory to areas of human behavior earlier left to sociologists and social psychologists, including work habits and addictions.

A popular author, Becker has also used a Web log he writes and an earlier long-running Business Week column to advocate sometimes unconventional views, including legalizing drugs in the United States and auctioning off immigration rights.