obesity

New research disputes fat but fit claim 

Dec. 2, 2013 at 5:16 PM ET

Video: A big study out Monday says there’s no such thing as healthy obesity. Good lab values don’t protect people from the effects of fat. If your BMI is in the overweight category, NBC’s Dr. Nancy Snyderman warns, you should not be complacent.

If you're overweight or obese, it may pay off to shed even just a few extra pounds.

Excess weight can knock years off your life even if your cholesterol, blood pressure and blood sugar are in the healthy range, a new study suggests.

Scrutinizing the combined data from eight earlier studies, Canadian researchers have concluded that there is no such thing as “healthy obesity,” according to a report published in the Annals of Internal Medicine.

Just having good metabolic numbers doesn’t protect you from fat’s deleterious effects, said study co-author Dr. Bernard Zinman, a professor of medicine at the University of Toronto and director of the diabetes center at the Mount Sinai Hospital in Toronto.

Some health professionals have “coined the term ‘healthy obesity,’” Zinman said. “When we performed a systematic review of studies that followed people for more than 10 years, indeed, even in those who were metabolically pristine, there was still an increased risk of cardiovascular death and heart attack. Healthy obesity is a myth.”

To take a closer look at how excess pounds affect heart health, Zinman and his colleagues combed through the scientific literature searching for studies that looked not only at life expectancy and body mass index, but also at metabolic measurements such as blood sugar, blood pressure and cholesterol. They chose to focus in on eight studies that when combined included information from a total of 61,386 volunteers. Four of the studies included in the researchers’ meta-analysis had follow-ups of more than 10 years.

When Zinman and his colleagues looked only at data from studies with long-term follow-up and focused just on individuals who were “metabolically healthy,” they found that obesity raised the risk of death, heart attack, and stroke by 24 percent. Similarly, they found that people who were metabolically healthy but overweight had a 21 percent increased risk, but that finding was not statistically significant.

By the same token, people who were “metabolically unhealthy,” had a higher risk of death, heart attack and stroke, whether they were fat or thin.

The report seems to contradict a study published earlier this year, which had concluded that overweight individuals might actually be healthier than those with normal weights.

But the differing results may simply be due to the fact that the new report looked at different data and at long-term outcomes, experts said. Conclusions can be skewed when young, muscled up men are included because even though they have little body fat, they will have a high BMI, said Dr. David Heber, a professor of medicine and director of the Center for Human Nutrition at the University of California, Los Angeles. And most studies are using BMI as a proxy for body fat.

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The conclusions of the new study fall in line with other research that’s shown that fat, in and of itself, is a risk factor for heart disease, Heber said.

The new study shows that we can’t be complacent about our weight, said NBC News health and diet editor Madelyn Fernstrom. Still, a population study like this one can’t predict an individual’s risk, Fernstrom added.

The only way to know how worried you should be about your weight is to have “a frank discussion with your doctor,” Fernstrom said. Mitigating factors could include your family history and fitness, she added.

People who might be jolted into action by the new study should realize that even small changes in lifestyle can result in big differences, experts said.

You don’t need to be pencil thin, said Dr. Rexford Ahima, a professor of medicine and director of the obesity unit at the Institute for Diabetes, Obesity and Metabolism at the University of Pennsylvania Medical Center.

“There is such a thing as healthy weight,” Ahima said. “But it’s not going back to where you were in high school. If you’re overweight or obese, you should aim to be 5 to 10 percent less than you are today. Many studies have shown that a 5 to 10 percent weight reduction can impart benefit.”

And for those who have trouble losing weight, improved fitness may be the key to healthier living, said Dr. Vicki March, medical director of the Healthy Lifestyle Program at Magee-Womens Hospital of the University of Pittsburgh Medical Center and co-director of BodyChangers, also at Magee.

“You’re not doomed if you don’t lose weight,” March said. “In this study, they didn’t take exercise and other habits into consideration. We’ve known for a long time that someone who is physically fit is healthier than someone who is not, no matter what weight they are.”

Even people who are obese can find ways to exercise and can become fitter, March said. “People who have high BMIs can ride bikes or swim,” she added.  

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