The Obesity Paradox

George T. Griffing, MD


April 14, 2009

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Two-thirds of Americans are obese or overweight, and the Centers for Disease Control has declared that obesity is at epidemic proportions in the United States.[1] Obesity is a risk factor for many diseases, such as diabetes mellitus, hypertension, stroke, and heart and renal disease. Despite this relationship, obese people with these diseases live longer than their normal-weight counterparts. This conundrum has been called the "obesity paradox."[2] But before you postpone your diet or have that extra jelly donut, let's examine the data.

The Obesity Paradox is best studied in congestive heart failure, showing that obese patients have a better prognosis than leaner ones.[3,4,5,6,7,8] Of note, none of the congestive heart failure trials have found obesity to worsen the prognosis.

The obesity paradox has also been described for other diseases, including coronary artery disease, hypertension, and stroke, and in dialysis patients.[9,10] Cachexia from advanced disease was at first thought to be the explanation. These findings, however, show a continuous dose-response reduction in mortality across a gradation of body mass index levels. And in many of these studies, the lowest body mass index was calculated to have a healthy percentage of body fat and not at levels consistent with a malnourished state.

How do we explain the obesity paradox? In short, the answer is unknown, but there are several possibilities. First, obese patients may present earlier with less disease burden. Second, obese patients may be more aggressively treated. Third, adipose tissue may secrete protective cytokines and other hormonal products. Finally, these findings are associative, but do not prove a cause-and-effect relationship.

So can we have our cake and eat it too? Based on the data at hand, it is likely that the obesity paradox is a real association, but what it means for the recommendations and treatment of our patients is food for thought.

That's my opinion. I'm Dr. George Griffing, Professor of Medicine at St Louis University and Editor-in-Chief for Internal Medicine at eMedicine.


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