THURSDAY, Oct. 22, 2015 (HealthDay News) — Scientific debate continues to simmer over the so-called “obesity paradox” — the apparent ability of obese or overweight people to better withstand chronic illnesses, such as diabetes or heart disease, and outlive thinner people with those same maladies.
But the obesity paradox is built on a foundation of shaky research, a new study contends. Earlier studies failed to account for two important factors that negate the supposedly protective effects of obesity: weight history and smoking, the researchers said.
People who are seriously ill tend to lose weight as they near death, the study authors explained. And that fact influences the data enough to create the false perception of an obesity paradox, argued lead author Samuel Preston, a professor of sociology at the University of Pennsylvania in Philadelphia.
Previous studies also have failed to account for smoking, which is incredibly unhealthy but also tends to ramp up a person’s metabolism and keep them slim, Preston added. Smokers are less likely to be obese, and those who are obese are less likely to smoke, the study authors said.
“When we adjust for those biases, we reverse the obesity paradox in people with cardiovascular disease,” he concluded. “The obesity paradox exists, but the cause of it is not the benefit of being overweight. The principal causes of the paradox are these two biases.”
For the study, researchers examined data from more than 30,000 people participating in the U.S. National Health and Nutrition Examination Survey between 1988 and 2011. The study focused on the nearly 3,400 who had heart disease.
Most studies that have looked at the possibility of an obesity paradox only included a person’s weight when they are surveyed, Preston said.
For example, a 300-pound man might have dropped a third of his weight within the last month due to illness, but the study would count him as always weighing 200 pounds.
This time, the research team opted to include weight history. That way, they could include the health risks of long-term obesity in their analysis, even if someone had recently lost weight, Preston explained.