Baby boomers who were even just a tad pudgy were more likely to die prematurely than those who were at a healthy weight, U.S. researchers reported Tuesday.
While obesity has been known to contribute to early death, the link between being overweight and dying prematurely has been controversial. Some experts have argued that a few extra pounds does no harm.
However, this is one of the first major studies to account for the factors of smoking and chronic illness, which can complicate efforts to figure out how much weight itself is responsible for early death.
"The cumulative evidence is now even stronger," said Dr. Michael Thun, chief epidemiologist of the American Cancer Society who had no role in the research. "Being overweight does increase health risks. It's not simply a cosmetic or social problem."
A separate large study of Korean patients, also released Tuesday, reached the same conclusion. Both are being published in this week's New England Journal of Medicine.
An estimated two-thirds of Americans adults are overweight or obese, according to federal statistics. Obesity raises the risk of heart disease, diabetes, arthritis and some cancers. Being overweight increases blood pressure and cholesterol levels, which in turn could lead to heart disease.
The latest studies contradict controversial research by the federal Centers for Disease Control and Prevention last year that suggested being a little plump isn't so bad. Since then, CDC chief Dr. Julie Gerberding distanced herself from the report and acknowledged potential flaws in the study that included people with health problems who tend to weigh less.
The U.S. study, by scientists at the National Cancer Institute, involved more than half a million people, ages 50 to 71, participating in a research project by the National Institutes of Health and AARP, formerly known as the American Association of Retired Persons.
Researchers analyzed patients' body-mass index and mortality rate over a 10-year period from questionnaires they filled out in 1995 and 1996 detailing their weight and diet.
Under current government standards, a BMI — or weight-to-height measurement — of 25 or higher is overweight; 30 and above is obese.
Generally, you must be 30 pounds overweight be to considered obese. Using the body-mass index, a 5-foot-10 man would be considered overweight if he is between 174 to 208 pounds, and obese at 209 pounds or more.
Overall, baby boomers who were underweight or obese had an increased risk of death compared with normal-weight people. The risk was particularly high for Hispanics, Asians and American Indians than for whites and blacks. However, people who were merely overweight had no substantial increased risk.
But in a separate analysis of 186,000 healthy people — who had never smoked — overweight people were 20 to 40 percent more likely to die prematurely than normal-weight people. The risk increased two- to three-fold for obese people.
CDC spokeswoman Karen Hunter declined to comment on the federal study, saying the public health agency does not comment on research done by other government branches.
In a separate study of 1.2 million Korean patients, ages 30 to 95, researchers from the Yonsei University in South Korea and Johns Hopkins University's Bloomberg School of Public Health reported similar findings.
Among about half a million healthy non-smokers, overweight people had a 10 to 50 percent greater risk of dying from heart disease or cancer than normal-weight people.
The two studies clearly show that being overweight "is not a benign condition," said Dr. Frank Hu, an epidemiologist and obesity researcher at the Harvard School of Public Health.
"The public health message should be loud and clear: Maintaining a healthy weight and preventing weight gain in middle age is important to maintaining longevity," said Hu, who was not connected to the research.
In an accompanying editorial, Dr. Tim Byers of the University of Colorado recommended taking "small steps toward weight control, such as short bursts of activity" and changes to diet.
Several years ago, Byers eliminated powdered doughnuts from his diet and lost 10 pounds. With a current BMI of just over 27, he looks for other ways to shed the weight like climbing stairs instead of taking the elevator to his fourth-floor office.