Old age is far from kind to the body, as the unfortunate truth goes. So when the theory surfaced that growing older could shield people from the increased risk of death associated with obesity, some rejoiced at the idea that their later years could be extended in spite of (or because of) imperfect health.
The "obesity paradox" has been researched extensively, and scientists have seen better-than-expected outcomes for obese patients with conditions as serious as heart failure and cardiovascular disease. Dr. Carl J. Lavie made waves in the medical world with his study of the phenomenon, Obesity and Cardiovascular Disease.
"Obesity is a major problem that contributes significantly to increased risk of heart disease and mortality," Lavie said. "But once you get high blood pressure, blocked heart arteries, and peripheral arterial disease, the obese patients do better than the lean patients. The obesity paradox has been written about for years, but still many doctors are not aware of it."
Sound too good to be true? It did to Dr. Ryan Masters and his fellow researchers at Columbia's Mailman School of Public Health, who published contradictory research last week in the American Journal of Epidemiology.
Using data from the U.S. National Health Interview Survey and the National Death Index of people ages 25 to100, the researchers found that previous evidence supporting the obesity paradox may have been flawed, giving the impression that obesity offers an advantage to older people.
However, Masters said, “the obesity-mortality association is not as large as expected, and often appears to be robust only among the extremely obese.” He said that the association between obesity and an increased risk of death is grounded in conventional ideas of how obesity affects the body, particularly in old age.
“Our current findings suggest that, indeed, the obesity-mortality association is strongly biased by selection effects, and once these are accounted for the effect of obesity on mortality risk grows stronger with age," he said.
Flaws in the Data
Masters blames biases in previous research data for propagating the idea that obesity can act as a barrier to mortality in the elderly.
“When researchers have looked at variation in the ways obesity affects mortality by age they have given little thought to biases that might exist in the data they’ve used," Masters said. "They’ve simply presumed that the samples are truly random. But it's likely that the samples are biased, especially at older ages, and this bias is likely more pronounced among the obese population.”
For example, the data used to draw the "obesity paradox" conclusion excluded people who were institutionalized in hospitals and nursing homes, a group that includes many seniors. Moreover, the data gathered for people 65 years old and older necessarily left out those who did not live to see 65, including many obese individuals who died from co-morbidities like heart attacks and strokes.
In the debate over the "obesity paradox," the very notion of what constitutes good health is at stake.
“To give [the obesity paradox] credence bolsters the flippant and dismissive responses some scholars and media personnel have made to rapidly rising rates of obesity in the U.S. population,” Masters said. “That is, the obesity paradox has been used to dismiss the public health worry about rising obesity rates as a moral panic. We think such dismissal is premature, and greater attention needs to be paid to the deleterious health consequences of high body mass on the U.S. population’s health.”
Can Obesity Really Be Healthy?
No doctors, whether they believe in the "obesity paradox" or not, would encourage patients to gain excess weight or remain obese in order to better fight mortality down the road.
“Obesity is not a status that instantly translates into poor health and shorter life, but rather has a latent, cumulative, compounding toll,” Masters said. “The greater duration of time spent obese the greater the effect on health and longevity. Thus, I think it’s imperative to intervene early and be mindful of nutrition and exercise across the entire life course.”