[Abstract below]
Bad news for all those baby boomers starting to pile on the pounds as they go through middle age: You don't have to be obese — just a little overweight — to increase your risk of dying prematurely, according to a large government study.
The 10-year study of more than 500,000 U.S. adults found that those who were just moderately overweight in their fifties were 20 percent to 40 percent more likely to die in the next decade. Another study involving more than 1 million Korean adults, also being published in this week's New England Journal of Medicine, produced similar results.
The studies, both released yesterday, were aimed at helping resolve a long debate over whether the millions of Americans who are not obese but are nevertheless considered overweight are at significant risk.
"These findings are very important," said Michael F. Leitzmann of the National Cancer Institute, which led the U.S. study. "A substantial proportion of the population in the U.S. is overweight. So if overweight is related to premature death, that's very important to public health."
The findings are particularly relevant to the large number of baby boomers who are going through that critical period of middle age when people typically gain weight.
"What we need to do is try to encourage people to maintain a healthy weight and avoid weight gain," Leitzmann said.
The findings were welcomed by public health and obesity experts as powerful new evidence that people should do whatever they can to maintain a healthy weight.
"The take-home message is that if you are not obese but just overweight, it's still a good idea to lose weight," said Thomas A. Wadden, president of the Obesity Society. "It's kind of a bummer, but maybe this will help motivate people that it's time to do something about their weight."
Skeptics, however, remain unconvinced, saying the analysis is flawed and will alarm people unnecessarily.
"I think they are just adding to the obesity hysteria," said Glenn A. Gaesser of the University of Virginia. "They are presenting the data in a way that paints overweight and obesity in the worst possible light. It's not as bad as they make it seem."
The number of Americans who are overweight has been increasing steadily in the United States. About two-thirds of Americans are now overweight, including about a third who are obese. Anyone with a body mass index (BMI) between 25 and 29.9 is considered overweight, whereas a BMI of 30 or above is considered obese. (A 5-foot-10-inch adult who weighs between 174 and 208 pounds is considered overweight; above that is considered obese.)
Studies clearly show that obesity increases the risk for a host of ailments — including heart disease, diabetes, cancer and arthritis — and that obese people are more likely to die prematurely.
Although people who are overweight but not obese have been found to have an increased risk of diabetes and are more likely to have high blood pressure and cholesterol levels that put them at increased risk of heart attacks, it has been unclear whether they are more likely to die prematurely. Previous studies have produced conflicting results, including a major study by the federal Centers for Disease Control and Prevention that indicated that being slightly overweight might actually be protective.
In the hope of helping settle the question, the National Cancer Institute launched the new study, involving 527,265 men and women ages 50 to 71. The researchers asked the subjects detailed questions about their health and lifestyles, including their diet and physical activity, as well as their height and weight, including how much they weighed when they were 50.
After a decade, the researchers found that those who were moderately overweight when they were 50 were at significantly elevated risk of dying prematurely, and those who were obese were two to three times as likely. Just being overweight was not nearly as dangerous, but it still boosted the risk by 20 to 40 percent, the study found.
The researchers and others said the findings are particularly noteworthy because of the study's size and the fact that the analysis controlled for the effects of smoking and illness. That may explain some of the earlier findings — smokers and sick people tend to weigh less.
"Those factors can confuse the true relationship between weight and health," said Tim Byers of the University of Colorado School of Medicine, who wrote an article accompanying the study.
But other researchers were not convinced, saying the findings are questionable for a number of reasons, including the fact that the weight data relied on the participants' recollections, which are notoriously unreliable, instead of direct measurements. Also, the sample was not necessarily representative of the general population, they said.
"I feel like the researchers were trying to manipulate their data to match their conclusion," said Linda Bacon of the University of California at Davis. "I think it's very threatening to people to be open to the idea that overweight may not be as bad as we think."
While acknowledging those potential problems, the researchers and others said they believe that the new findings are more reliable than those of earlier studies and are particularly important because they looked at a relatively recent sample of baby boomers. Some researchers had speculated that advances in health care might offset the negative effects of being overweight.
"It's a very important paper," said JoAnn Manson of the Harvard School of Public Health. "The study included many members of the baby-boomer generation. So the results, unfortunately, portend a large burden of chronic disease and excess mortality in upcoming decades in that generation."
Other researchers said they hope to move the debate beyond arguing over what level of being overweight is dangerous to focusing on finding better ways to prevent people from gaining weight in the first place.
"Proving yet again that being overweight is unhealthy is less helpful than trying to figure out what to do about it," said Kelly D. Brownell of Yale University.
source: http://www.washingtonpost.com/wp-dyn/content/article/2006/08/22/AR2006082201180.html 23aug2006
Kenneth F. Adams, Ph.D., Arthur Schatzkin, M.D., Tamara B. Harris, M.D., Victor Kipnis, Ph.D., Traci Mouw, M.P.H., Rachel Ballard-Barbash, M.D., Albert Hollenbeck, Ph.D., and Michael F. Leitzmann, M.D.
ABSTRACT
Background
Obesity, defined by a body-mass index (BMI) (the weight in kilograms divided by
the square of the height in meters) of 30.0 or more, is associated with an
increased risk of death, but the relation between overweight (a BMI of 25.0 to
29.9) and the risk of death has been questioned.
Methods
We prospectively examined BMI in relation to the risk of death from any
cause in 527,265 U.S. men and women in the National Institutes of Health–AARP
cohort who were 50 to 71 years old at enrollment in 1995–1996. BMI was
calculated from self-reported weight and height. Relative risks and 95 percent
confidence intervals were adjusted for age, race or ethnic group, level of
education, smoking status, physical activity, and alcohol intake. We also
conducted alternative analyses to address potential biases related to
preexisting chronic disease and smoking status.
Results
During a maximum follow-up of 10 years through 2005, 61,317 participants (42,173
men and 19,144 women) died. Initial analyses showed an increased risk of death
for the highest and lowest categories of BMI among both men and women, in all
racial or ethnic groups, and at all ages. When the analysis was restricted to
healthy people who had never smoked, the risk of death was associated with both
overweight and obesity among men and women. In analyses of BMI during midlife
(age of 50 years) among those who had never smoked, the associations became
stronger, with the risk of death increasing by 20 to 40 percent among overweight
persons and by two to at least three times among obese persons; the risk of
death among underweight persons was attenuated.
Conclusions
Excess body weight during midlife, including overweight, is associated with an
increased risk of death.
Source Information
From the Nutritional Epidemiology Branch (K.F.A., A.S., T.M., M.F.L.),
Division of Cancer Epidemiology and Genetics and the Biometry Research Group (V.K.),
Division of Cancer Prevention, and the Division of Cancer Control and Population
Sciences (R.B.-B.), National Cancer Institute, and the Laboratory of
Epidemiology, Demography, and Biometry, National Institute on Aging (T.B.H.),
the National Institutes of Health, Bethesda, Md.; and the AARP, Washington, D.C.
(A.H.).
Address reprint requests to Dr. Adams at the Nutritional Epidemiology Branch, 6120 Executive Blvd., Suite 320, Rockville, MD 20852, or at adamske@mail.nih.gov
source: http://content.nejm.org/cgi/content/short/355/8/763 23aug2006
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