American scientists have sounded a warning that obesity is now a much bigger threat to the population's health than smoking. Ever expanding waistlines now seem to be a cause for much concern as these causes more diseases than tobacco.

Also, obesity cuts back as much healthy lifespan as smoking does.

For years, experts and researchers have been predicting that there would come a time when there would be more of obesity and less of smoking, and then the former would be a much bigger threat, and the times seems to have come now.

The Quality-Adjusted Life Years because of both smoking and obesity were calculated by researchers from Columbia University and the City College of New York, and the results presented have been based on interviews of 3.5 million adults countrywide in the largest ongoing health study in the US.

The number of smokers declined by 18.5% between 1993 and 2008, but the obesity numbers rose by 85%, and while smoking was found to be the cause of more deaths, obesity caused more illnesses.

Experts are now warning that the rise in obesity could result in the first decline in life expectancy in about 200 years.