Health Gains From Lowered Smoking Rates in Jeopardy

Dec. 3 -- WEDNESDAY, Dec. 2 (HealthDay News) -- The overall health of the U.S. population has improved over the past three decades, largely because people have quit smoking in droves, but a new study suggests those gains might soon be wiped out if the rising obesity rates among Americans don't level off or drop.

If current trends in both smoking and obesity continue unchanged, the average life expectancy in America will be reduced by almost nine months, according to the study, which is published in the Dec. 3 issue of the New England Journal of Medicine.

On the other hand, the researchers calculated what would happen if everyone in America maintained a normal weight and no one smoked. If these two behavior changes were to occur, Americans would gain nearly four years of life.

"Although overall life expectancy is likely to increase, when we look at these two unhealthy behaviors we see the potential that it could have risen this much higher without obesity and smoking," said study author Susan Stewart, a research specialist in aging at the National Bureau of Economic Research in Cambridge, Mass.

"Even small improvements in these risk factors can make a difference," she added.

It's estimated that obesity is responsible for between 5 percent and 15 percent of deaths each year in the United States, according to background information in the study. Smoking still accounts for about 18 percent of deaths each year.

Along with their effect on mortality, obesity and smoking can both have a large impact on quality of life as well.

For the current study, the researchers used data from three nationally representative surveys that included data from as far back as 1971 through 2006.

The researchers projected that past trends in obesity and smoking would continue, which meant that obesity rates would continue to increase, while smoking rates would continue to drop. The researchers estimated that if current trends continue, nearly half of the U.S. population will be obese by 2020.