Obesity Paradox Doesn’t Hold Up

Posted on: October 9, 2015 Topics: cardiovascular disease, Global Health, obesity, smoking

ObesitySmokingA study co-authored by Andrew Stokes, assistant professor of global health, shows obesity does not protect patients with cardiovascular disease.

Study after study has shown obese or overweight people with cardiovascular disease outliving their normal weight counterparts—the so-called obesity paradox.

Stokes and Samuel Preston, professor of sociology at the University of Pennsylvania, set out to solve the puzzle.

By accounting for weight history, and adding in smoking as a factor, the researchers found the paradox no longer holds up.

Stokes and Preston started with data from more than 30,400 participants of the National Health and Nutrition Examination Survey between 1988 and 2011. The survey is a nationally representative sample considered the gold standard in the United States. Of those participants, 3,388 had cardiovascular disease.

Most research of this type looks only at weight at time of survey. For example, if a participant who used to weigh 300 pounds lost one-third of their mass by the time of weigh in, they would be counted as 200 pounds.

Including weight history is a key innovation, says Stokes. Not doing so “would be like classifying a lifelong smoker who quit the day before the survey as a non-smoker.”

Weight history “turns out to have a profound effect on the findings,”  eliminating the mortality advantage for those who are overweight or obese.

Stokes and Preston also limited their pool to lifelong non-smokers. Smokers are less likely to be obese, and those who are obese are less likely to smoke. This correlation is even stronger for those with cardiovascular disease.

Accounting for weight history makes the obesity paradox disappear. Incorporate smoking, and being obese equates to significantly higher mortality for those with cardiovascular disease.

The researchers said these results could improve disease treatment, since some clinicians may use the obesity paradox in patient care decisions.

Read their full paper in the journal Obesity.

A version of this story first appeared at PennNews.


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One comment

  1. BMI, not just weight has been found to have this same paradox. It can be explained, in part to decreased height. A person may not change weight, but may increase in BMI due to decreased height, a common finding as individuals age. The formula for BMI (body mass divided by the square of body height) is particularly sensitive to changes in height, as height is squared. Since the squared height is in the denominator, as height decreases, BMI will increase.

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