Study suggests lower death risk for the overweight
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A century ago, Elsie Scheel was the perfect woman. So said a 1912 article in The New York Times about how Scheel, 24, was chosen by the "medical examiner of the 400 'coeds' " at Cornell University as a woman "whose very presence bespeaks perfect health."
Scheel, however, was hardly model-thin. At 5 feet 7 inches and 171 pounds, she would, by today's medical standards, be clearly overweight. (Her body mass index was 27; 25 to 29.9 is overweight.)
But a new report suggests that Scheel may have been onto something. The report on nearly 3 million people found that those whose BMI ranked them as overweight had less risk of dying than people of normal weight. And while obese people had a greater mortality risk overall, those at the lowest obesity level (BMI of 30 to 34.9) were not more likely to die than normal-weight people.
The report, although not the first to suggest this relationship between BMI and mortality, is by far the largest and most carefully done, analyzing nearly 100 studies, experts said.
But don't scrap those New Year's weight-loss resolutions and start gorging on fried Belgian waffles or triple cheeseburgers.
Experts not involved in the research said it suggested that overweight people need not panic unless they have other indicators of poor health and, that depending on where fat is in the body, it might be protective or even nutritional for older or sicker people. But overall, piling on pounds and becoming more than slightly obese remains dangerous.
"We wouldn't want people to think, 'Well, I can take a pass and gain more weight,'" said George Blackburn, associate director of Harvard Medical School's nutrition division.
Rather, he and others said, the report, in The Journal of the American Medical Association, suggests that BMI, a ratio of height to weight, should not be the only indicator of healthy weight.
"Body mass index is an imperfect measure of the risk of mortality," and factors like blood pressure, cholesterol and blood sugar must be considered, said Samuel Klein, director of the Center for Human Nutrition at Washington University School of Medicine in St. Louis.
Steven Heymsfield, executive director of the Pennington Biomedical Research Center in Louisiana, who wrote an editorial accompanying the study, said that for overweight people, if indicators like cholesterol "are in the abnormal range, then that weight is affecting you," but that if indicators are normal, there's no reason to "go on a crash diet."
Experts also said the data suggested that the definition of "normal" BMI, 18.5 to 24.9, should be revised, excluding its lowest weights, which might be too thin.
The study did show that the two highest obesity categories (BMI of 35 and up) are at high risk.
"Once you have higher obesity, the fat's in the fire," Dr. Blackburn said.
Still, it is possible that overweight or somewhat obese people are less likely to die because they, or their doctors, have identified other conditions associated with weight gain, like high cholesterol or diabetes.
"You're more likely to be in your doctor's office and more likely to be treated," said Robert Eckel, a past president of the American Heart Association and a professor at University of Colorado.
Some experts said fat could be protective in some cases, although that is unproven and debated. The study did find that people 65 and over had no greater mortality risk even at high obesity.
"There's something about extra body fat when you're older that is providing some reserve," Dr. Eckel said.
And studies on specific illnesses, like heart and kidney disease, have found an "obesity paradox," that heavier patients are less likely to die.
Still, death is not everything. Even if "being overweight doesn't increase your risk of dying," Dr. Klein said, it "does increase your risk of having diabetes" or other conditions.
Ultimately, said the study's lead author, Katherine Flegal, a senior scientist at the Centers for Disease Control and Prevention, "the best weight might depend on the situation you're in."
First Published January 2, 2013 12:00 am