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How the Obesity Paradox Works

Obesity Paradox Criticisms

Doctors still aren't sure that the obesity paradox is real.
Doctors still aren't sure that the obesity paradox is real.

There are many reasons to be skeptical of the obesity paradox, but the UCLA researchers have posed some biological explanations for it [source: Kalantar-Zadeh].

  • The adverse effects of obesity take more time to develop than those of chronic disease (heart failure, kidney disease). Therefore, the consequences of wasting kill patients much faster than obesity does.
  • In both CHF and chronic kidney disease, malnutrition and inflammation are common. These conditions alone could reduce the survival of these patients. Therefore, weight gain could be an indicator of better nutrition and, therefore, improved chances of survival in obese patients.

Dr. Kalantar-Zadeh argues that dietary restrictions placed on CHF and chronic kidney disease patients my actually be harmful to these patients. He advocates a "reverse epidemiology" approach to these conditions.


So, the obesity paradox has been observed in several clinical settings (CHF, chronic kidney disease), but physicians and scientists still aren't sure that it's a real phenomenon. Not many researchers have proposed biological hypotheses to explain the obesity paradox. There have been no direct animal studies or clinical trials that could address cause-and-

effect relationships. So, based on evidence available at this time, we can't conclude that the obesity paradox is real, certainly not enough to alter treatment for patients with CHF and chronic kidney disease. But many scientists think that research should be aimed at resolving the obesity paradox. It may have implications for changing treatment options for these patients.

Dr. Kalantar-Zadeh and colleagues also argue that the risk factors for the general population may not be applicable to the obese population. The obesity paradox is one example of this idea, which has been called reverse epidemiology. Imposing dietary restrictions on obese chronic disease patients, they say, may actually be harmful. The group cites a number of conditions where phenomena like the obesity paradox have been observed [source: Kalantar-Zadeh].

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