Obesity May WipeOut Benefit of Anti-Smoking Effort

About 40 years of health improvements from declining numbers of smokers may be undermined because too many U.S. adults are obese, researchers said.

Under one scenario of obesity and smoking trends, by 2020 the future life expectancy of a typical 18-year-old would be shortened 8 months, according to a study published today in the New England Journal of Medicine.

The number of adults who were obese more than doubled in 25 years to 72 million people, or 34 percent of U.S. adults, in 2006, according to the U.S. Centers for Disease Control and Prevention. Public-health programs and rising cigarette taxes reduced smoking rates to 21 percent in 2008 from 37 percent in 1970, according to the CDC.

“We found that in a horse race between obesity and smoking, obesity won, in a bad way,” said Susan Stewart, an author of the study and a researcher at the National Bureau of Economic Research, a nonprofit, nonpartisan group based in Cambridge, Massachusetts.

Obesity-related medical costs reached $147 billion in 2008, or about 10 percent of U.S. medical spending, according to a CDC study published July 27. Other studies have found the obesity epidemic threatens efforts to reduce deaths from heart disease and breast cancer.

Today’s analysis found obesity accounts for 5 percent to 15 percent of U.S. deaths each year, while smoking is tied to 18 percent of deaths. Failing to change continuing increases in obesity could erode the steady gains in health seen in recent decades.

National Health Assessment

Researchers from Harvard University, the University of Michigan and the economic research bureau used data from three large U.S. health assessment surveys to forecast life expectancy through 2020. Obesity was defined as having a body-mass index of 30 or greater, or about 192 pounds for person who is 5 feet 7 inches tall. Body-mass index is a method to determine body fat.

“If past obesity trends continue unchecked, the negative effects on the health of the U.S. population will increasingly outweigh the positive effects gained from declining smoking rates,” the authors wrote in the study.

The effort to reduce smoking “is probably one of the greatest health achievements in the 20th century,” said Sara Bleich, an obesity researcher at Johns Hopkins University’s Bloomberg School of Public Health in Baltimore, who wasn’t involved with the study. “Reduction of obesity should be the primary focus of public health efforts in the 21st century.

As of 2005, a typical 18-year-old male was expected to live to about age 76, while an 18-year-old woman would live to about age 81, according to the U.S. Social Security Administration.

Reduced Life Expectancy

If current obesity and smoking trends continue, by 2020 the life expectancy ages would subtract 0.71 years, or 8 months from future gains, according to today’s research.

If every U.S. adult stopped smoking and reached a normal weight, life expectancy for an 18-year-old would increase by 3.76 years, the authors estimated.

“Life expectancy will continue to rise but less rapidly than it otherwise would have” because of obesity, the researchers wrote.

The study is a “sophisticated analysis’” of the comparative risks of obesity and smoking in the general public, Bleich said in an interview. The study wasn’t designed to examine variations by race and ethnicity, which may produce “important differences” in life expectancy, she said.

Future Trend

The authors said recent data suggest U.S. obesity rates “may be decelerating.” About 32 percent of children ages 2 to 19 were at risk for being overweight or obese from 2003 to 2006, according to a study published in the Journal of the American Medical Association in May 2008. The high rates in children mean increases in obesity among adults are “likely to occur,” the researchers wrote.

Policy and environmental factors may cause obesity rates to change, the authors said.

“It could vary from someone inventing a pill that gets rid of obesity to someone developing a therapy that markedly changes the care for diabetes or heart disease,” Allison Rosen, an author of the study and researcher at the University of Michigan’s School of Public Health in Ann Arbor, Michigan, said in an interview.

San Diego-based Arena Pharmaceuticals Inc., Mountain View, California-based Vivus Inc. and Orexigen Therapeutics Inc. of La Jolla, California, are developing late-stage weight-loss drugs aimed at people who are obese.

The study was funded by the National Institute on Aging, Harvard University and the Albert and Mary Lasker Foundation, a New York-based a nonprofit biomedical research organization.

Bloomberg