A puzzle had been unsettling demographers Samuel Preston of the University of Pennsylvania and Andrew Stokes of Boston University for quite a while and they set out to demystify it. This phenomenon is referred to as the obesity paradox and the researchers wondered if it would hold up even when approached within different parameters?
The results of their study were published recently in the journal Obesity and according to their findings, the answer is no'. It was seen that obesity is harmful, not helpful, to someone with cardiovascular disease when accounting for weight history in addition to weight at the time of survey and when adding in smoking as a factor. Preston, a sociology professor in Penn’s School of Arts & Sciences said that there are claims which say that it is a good thing to be obese when you have cardiovascular disease, that if you have fat stores, maybe you’ll live longer. While it is conceivable that there are health advantages, the study show such people are overwhelmed by the disadvantages of being obese, once the two sources of bias are controlled.
The data from more than 30,400 participants from the National Health and Nutrition Examination Survey between 1988 and 2011 was used by Stokes and Preston. The survey is a nationally representative sample considered the gold standard in the United States. Of all the participants considered, 3,388 had cardiovascular disease. Most research of this kind only looked at weight at time of survey. Say like, if a participant who has always weighed 300 pounds lost 100 pounds by the time he weighed in, he would be counted at 200 pounds. So, Stokes and Preston innovated a bit and decided to opt for weight history.
Stokes, who earned both his master’s degree and Ph.D. from Penn and is now an assistant professor in the department of global health at BU, said that it was definitely a new and good idea. If we didn't do that, all the classification would be sort of messed up it would be akin to classifying a lifelong smoker who quit the day before the survey as a non-smoker even though he would carry the risk of smoking over even after he quit smoking.
With the help of this step, the researchers were able to identify a control group of people who had been normal weight their whole lives, those considered low-risk for disease. Stokes added that adding weight history did have a profound effect on the findings as it eliminated the mortality advantage for those who are overweight or obese. Including the second factor smoking further contributed to resolving the paradox. Typically, smokers are less likely to be obese, and those who are obese are less likely to smoke. So, the researchers limited their pool to lifelong non-smokers.
The results were quite surprising by accounting for weight history, the obesity paradox practically disappeared. When smokers were excluded obese equated to significantly higher mortality for those with cardiovascular disease.
Preston said that it is likely that clinicians are somewhat confused and in some cases, it is seen that they do that being overweight or obese is a good thing among people with cardiovascular disease, diabetes and other conditions for which a paradox has been demonstrated. The researchers said these results are significant and could improve disease treatment, as it may help clear confusion of clinicians who resort to the obesity paradox in patient care decisions.
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