Junkfood Science: “Obesity Paradox” #2— How can it be a disease if it has health benefits?

December 12, 2006

“Obesity Paradox” #2— How can it be a disease if it has health benefits?

“Obesity paradox” is a funny term when you think about it. It’s only a paradox — that fat people generally live longer than thin people — because it runs contrary to what a lot of people have come to believe. All we hear nowadays is that being fat is a disease and virtually every health problem experienced by fat people is somehow uniquely horrific.

So, you probably didn’t hear about the study, published in this month’s journal Hemodialysis International, led by Kamyar Kalantar-Zadeh, MD, PhD, MPH, of UCLA David Geffen School of Medicine. It reported that among dialysis patients, “obese” patients are far more likely to survive than smaller patients. Since dialysis patients have protein-energy malnutrition and inflammation, termed Kidney Disease Wasting, obesity probably represents better overall nutrition and protective reserves that lower their risk of death, said Dr. Kalantar-Zadeh.

According to these doctors, the popular belief that fatness is associated with heart disease among these patients has not been shown in any study, nor is the survival advantage of higher BMIs (body mass index) related to having greater muscle mass over fat. Fatness isn’t the only “paradoxical” association among favorable clinical outcomes of dialysis patients, they said in a 2005 issue of the American Journal of Clinical Nutrition:

High concentrations of total cholesterol have been associated with both a survival advantage in these patients, as has an inverse relation between blood pressure and outcome. These consistent findings across an array of cardiovascular risk factors in dialysis patients support the more inclusive term “reverse epidemiology.”

Reverse epidemiology has also been observed in heart failure patients, elderly persons, and patients with advanced malignancies, AIDS, and other chronic diseases. This means that 20 million persons—including almost half a million dialysis patients—in the United States alone may be subject to this reverse epidemiology. We believe this vulnerability to reverse epidemiology could have very important implications for public advice on health matters, because conventional recommendations for the management of CVD risk factors, such as weight reduction or aggressive treatment of hypercholesterolemia, may not be appropriate.

It’s probably shocking for some to hear that there even ARE health benefits to being fat. But as these doctors noted, kidney disease isn’t the only health problem where studies have shown that being fat appears protective and beneficial, especially as we age. It also includes infections, cancer, lung disease, heart disease, osteoporosis, anemia, high blood pressure, rheumatoid arthritis and type 2 diabetes.

“Both U.S. government and Swedish studies indicate that fatness is not associated with increased doctor visits, medical procedures or hospitalizations...Fat men took no more days of sick leave...and were no more likely to have work-limiting health conditions,” wrote Drs. Paul Ernsberger and Paul Haskew in The Journal of Obesity and Weight Regulations. Among those over age 60, “‘obese’ men and women are no more likely to suffer from chronic diseases than ‘average-weight’” persons.” But they are more likely to survive longer. (Yes, even when researchers have factored for weight loss that could be a symptom of late-stage cancer and other pre-existing illnesses that could make thinner groups appear less healthy.)

The Seven Country Study, for example, which has followed 13,000 men over the last 40 years, has found that the risks of dying from cancer and infections decrease with increasing weight. In long-term prospective studies, complications (like retinopathy) and mortality rates from type 2 diabetes are three times lower among heavier people. And people are much more likely to survive a hospitalization if they’re “overweight” than if they’re thin.

Not that any illness is entirely benign for any weight, but given the more favorable course among fat people for many conditions, it’s sad that it’s a perspective that has become lost in today’s popular discourse.

© Sandy Szwarc 2006

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