Obesity has overtaken smoking and is now a bigger threat to people's health, American scientists have warned.
Expanding waistlines now cause as much or more disease than tobacco, and do as much or more to shorten healthy lifespans, they say.
Researchers have predicted for years that as incidence of obesity increased and smoking fell, there would come a time when the damage caused by the first would outrank the second. Now it has happened.
Researchers from Columbia University and the City College of New York calculated the Quality-Adjusted Life Years (Qalys) lost due to both obesity and smoking. Qalys are an internationally recognised measure of health gain or loss associated with treatments, diseases or injuries.
The results are based on interviews with 3.5 million adults, the largest ongoing health study in the US. Between 1993 and 2008, the proportion of smokers fell by 18.5 per cent while the proportion who were obese rose by 85 per cent. Smoking was found to cause more deaths, but obesity caused more illness.
Experts on both sides of the Atlantic have warned that the rise in obesity could lead to the first decline in life expectancy in 200 years.
Haomiao Jia and Erica Lubetkin, who led the study which was published in the American Journal of Preventive Medicine, said: "Although life expectancy has increased over time, the increase in Qalys lost from obesity may result in a decline in future life expectancy. Such data are essential in setting targets for reducing modifiable health risks and eliminating health disparities."
Measures proposed to deal with the obesity explosion have included a so-called "fat tax" and a charge on fizzy drinks and colas, which are major contributors among young people.
In the UK, the British Medical Association narrowly defeated a proposal for a chocolate tax in 2008. Gordon Brown vetoed a Downing Street proposal for a fat tax in 2004, on the grounds that it would fall disproportionately on the poor.
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