Americans have increased their life expectancy by cutting back on cigarettes, but the pounds they're packing on mean that, ultimately, they could lose ground.
A New England Journal of Medicine study published Wednesday looked at previous national health surveys to forecast life expectancy and quality of life for a typical 18-year-old from 2005 through 2020. Declines in smoking over the last 15 years would give that 18-year-old an increased life expectancy of 0.31 years.
However, growing body mass index rates would also mean that that teen would have a reduced life expectancy of 1.02 years, giving a net life expectancy reduction of 0.71 years.
Researchers from Harvard University, the University of Michigan and the National Bureau of Economic Research say that although life expectancy may still increase in the future -- because of factors such as overall healthcare improvements, better nutrition and education -- rising obesity rates will eventually slow that progression.
"This is a bit of a wake-up call," says Dr. Allison Rosen, assistant professor of internal medicine and health management policy at the University of Michigan and a study co-author. "We have always attributed so many of our health problems to smoking, and this emphasizes that we're getting health improvements from declines in smoking. But changes in the rates of obesity are starting to outweigh the declines in smoking."
Included in the study was data from the National Health Interview Survey, the National Health and Nutrition Examination Survey and the Medical Expenditure Panel Survey. Researchers looked at past trends to predict future ones, and divided survey participants into four categories for smoking (such as current or former smoker) and four categories for body mass index, then cross-matched them to produce 16 groups. They approximated relative risks for death for all groups.
Dr. Ken Fujioka, director of the Scripps Clinic Center for Weight Management in Del Mar, points out that obesity's negative effects are omnipresent. "With smoking we know that people may get lung cancer or heart disease, but with obesity they can have a number of health issues, from multiple types of cancer to diabetes and high cholesterol. If you have to pick two evils, it's scary to think that smoking might be the lesser."
What's needed, says Donna Spruijt-Metz, associate professor of preventive medicine at USC's Keck School of Medicine, is a sea change in obesity policy and the environment, just as there was with smoking.
But this may be tougher, she adds. "It's one thing to stigmatize smokers, but it's an entirely different thing to stigmatize heavy people. It's a different animal."
When it comes to life expectancy, some Americans may rather have cheesecake now than an extra few months of life years down the road but, Rosen says, people should consider short-term benefits as well.
"I've had patients lose weight and stop smoking, and the changes in their quality of life can be dramatic. One patient lost 55 pounds, and before that he was in a wheelchair half the time. I know smokers who like to go run around with their friends, but they get short of breath and tired rapidly. Life expectancy may not come until years later, but you can experience quality of life right now."