Dr. Nortin Hadler, author of Worried Sick and Stabbed in the Back, is well-known for debunking medical myths. But in his latest book, Rethinking Aging (UNC Press), Hadler, a professor at the University of North Carolina, Chapel Hill, commits what some might call medical heresy, suggesting that, perhaps, as we approach middle-age, “It’s OK to be Overweight.”

Wait a minute. What is Hadler saying? Everyone knows that obese Americans are driving our health care bills to the moon. Some argue that they should pay higher insurance premiums. Meanwhile, those extra pounds are sending millions to an early grave. And we all know that if our obese neighbors would just put down their forks and get on a treadmill, the pounds would melt away.

But as is so often the case, what “everyone knows” just isn’t true.

Myth #1: The U.S. spends so much on health care in large part because too many of us are just plain fat.

Here, the conventional wisdom ignores a compelling 2007 McKinsey & Co. study which demonstrates that obesity does not begin to explain why, in 2005, we shelled out $480 billion more for health care than peer nations.

Make no mistake, obesity is expensive, and linked to a host of diseases–especially later onset diabetes.

But when McKinsey’s expert number-crunchers compared the prevalence and cost of 130 diseases (including obesity, heart disease and diabetes) in the U.S. and six other countries (Japan, Germany, France, Italy, Spain and the UK), they discovered that the U.S. spent under $25 billion treating all 130 conditions—a fraction of the “extra” $480 billion that we spent on health care.

Where did the other $455 billion go? First, we pay more for everything, from doctors’ services to medical devices. McKinsey’s analysts calculated that higher prices account for roughly $280 billion in “additional spending.” Secondly, “inefficiencies and complexities” in our health care system add another $150 billion to the tab. “Fee-for service” encourages doctors to see more patients. Finally, administration, regulation and the many go-betweens (brokers and agents) needed to deliver care in our fragmented system cost nearly $100 billion.” None of this is news.

Why, then, do we continue to blame the obese? The Incidental Economist’s Aaron Carroll explains: “when confronted with the numbers, people feel a need to find a reason. They need something to blame.  And no one ever wants to blame the system.”  In a culture that equates overweight with gluttony and sloth, it’s easier to blame the victim.

Myth #2: If they would just “eat less” and “move more” the problem would be solved.

If only it were that simple.  But as physicians who treat obese patients reveal in an eye-opening PBS documentary titled “Fat,” even when compliant patients diet and exercise under a doctor’s supervision, 95 percent regain whatever weight they lose.

The merely overweight can, in fact, lose fifteen pounds, and keep it off—if they do it very slowly, and focus on eating smaller portions.  (Those who buy into some of the quicker solutions offered by our $40 billion weight-loss industry are likely to find themselves shedding, and re-acquiring, the same 15 pounds, over and over again.)

The truly obese face a far more difficult problem. Obesity is an extraordinarily complicated disease caused by a combination of bio-chemical forces, genetics, and environment. Many physicians who don’t specialize in this area “still believe that obesity is caused by eating too much and not exercising enough, but such thinking is too simplistic,” says Dr Robert Lustig, an obesity expert at the University of California, San Francisco. “If it were that simple we would have solved it a long time ago,” adds Dr. Lee Kaplan, head of the Weight Reduction Program at Mass General.  “More than 400 genes are involved in weight regulation.”

No wonder some physicians tell obese patients to forget the diets and focus on exercise. Swim. Join a dance class. Their silhouettes won’t change, but they’ll be healthier.

Myth #3: Fat kills

Not necessarily true, says Hadler, pointing to two 2010 studies published in Obesity  and the Journal of the American Geriatrics Society which suggest that only the “morbidly obese” (with a body-mass index over 35)  and the “abnormally thin” (BMI under 18.5) “incur any increased risk of death before their time.” (A standard measure of heft, BMI considers both weight and height).  “Obese” subjects (BMI of 30-35) died no sooner than “normal folks.” Those who were “overweight” (BMI of 25-30) actually lived longer. Padding offers some protection, particularly for the elderly.  As for the underweight, apparently you can be too thin.

“In the past, we were fooled by studies that didn’t adjust for socioeconomic status,” Hadler explains. Many of the poor are obese, and they do die sooner than the rest of us. But obesity is not the major factor behind their premature deaths. What kills them is a combination of factors, with stress and tobacco at the top of the list.

Ultimately, studies reveal that fitness is more important than fat. Of course our highly profitable weight-loss industry does not want us to hear this.No one makes much money when you swim or jog.

As for Hadler, he recommends exercise for aging Americans, not because it will prolong your life (he’s skeptical), but because you will enjoy life more: “Try playing with a toddler,” writes Hadler, a grandfather who doesn’t weigh himself (he admits he’s probably overweight), but rides his bicycle over hill and dale 100 miles a week.

Maggie Mahar is the author of Money-Driven Medicine: The Real Reason Health Care Costs So Much and blogs at Reforming Health.

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