Obesity Will Snuff out Health Benefits
Gained by Smoking Declines
If obesity trends continue,
the negative effect on the health of the U.S. population will overtake
the benefits gained from declining smoking rates, according to a study
by University of Michigan (U-M) and Harvard researchers published in
the New England Journal of Medicine.
"Obesity plays a large role
in life expectancy," said co-author Allison B. Rosen, assistant
professor in the department of internal medicine at the U-M. "Despite
the fact that we are smoking less, body-mass indexes (BMI) are going
up. These increases in obesity are overtaking these changes in smoking
Using a technical analysis
that includes forecasting future trends based on historical data,
researchers found that despite declines in smoking, the remaining life
expectancy of a typical 18-year-old would be held back by 0.71 years by
the year 2020 because of the increased BMI of the general population.
The researchers also looked at quality of life. That same 18-year-old
could expect to give up 0.91 years of increased quality-adjusted life
If all U.S. adults became
nonsmokers of normal weight by 2020, their life expectancy would be
forecast to increase by 3.76 years or 5.16 quality-adjusted years.
However, the researchers say
the study's results don't imply that life expectancy will fall -- more
likely, life expectancy will continue to rise due to other factors, but
less rapidly than it otherwise would.
"In the past 15 years,
smoking rates have declined by 20 percent, but obesity rates have
increased by 48 percent," says lead author Susan T. Stewart, Ph.D, a
Harvard University research associate for the joint project of the
National Bureau of Economic Research and Harvard's Program for Health
System Improvement. "If past trends continue, nearly half of the
population -- 45 percent -- is projected to be obese by 2020."
In addition to better
managing clinical risk factors such as blood sugar among those who are
obese, effective public health efforts are needed to address the roots
of obesity, like sedentary lifestyles, the widespread availability of
high-calorie food in large portions and reduced time for the
preparation of food at home, says David Cutler, Ph.D., another
co-author of this study and professor of Economics at Harvard
University, as well as a research associate for the National Bureau of
Rosen said this study does
not indicate that people are getting heavier because they are not
smoking. The weight gain associated with quitting smoking is temporary
and thus not significant enough to drive the rising trend in increased
Public health efforts to
discourage smoking have worked, and a similar effort could help turn
around obesity rates, Rosen said. Many weight control interventions
have proven successful and their use should be encouraged.
"Losing weight is harder than
quitting smoking. People don't have to smoke to live. People have to
eat to live," she said.
"The hypothetical scenario of
having everyone a non-smoker of normal weight may be unachievable. But
these results show the dramatic toll that both smoking and obesity can
have on both the length of life and the quality of life."
The study was funded by the
National Institute on Aging, the Harvard Interfaculty Program for
Health Systems Improvement and the Lasker Foundation.
For more information on the
University of Michigan Health System, visit www.med.umich.edu