Death risk from obesity increases with age
Washington, February 6: The "obesity paradox" that says, at age 65 and older, having an elevated BMI won't shorten your lifespan, and may even extend it has been proved wrong in a new study.
Researchers have found that as obese Americans grow older, in fact, their risk of death climbs.
Ryan Masters, PhD, and Bruce Link, PhD, at Columbia University's Mailman School of Public Health, in collaboration with Daniel Powers, PhD, at the University of Texas argue that past studies of longevity and obesity were biased due to limitations of the National Health Interview Survey, or NHIS, which provides information on obesity.
The survey excludes individuals who are institutionalized, such as in a hospital or nursing home-a group largely made up of seniors. Consequently, the data is overrepresented by older respondents who are healthy, including the relatively healthy obese.
What's more, many obese individuals fail to make it to age 65-and thus do not live long enough to participate in studies of older populations.
"Obesity wreaks so much havoc on one's long-term survival capacity that obese adults either don't live long enough to be included in the survey or they are institutionalized and therefore also excluded. In that sense, the survey data doesn't capture the population we're most interested in," said Dr. Masters, a Robert Wood Johnson Foundation Health and Society Scholar at Columbia's Mailman School and the study's first author.
In his analysis Dr. Masters matched NHIS data on obesity with corresponding records in the National Death Index using data from close to 800,000 adults surveyed between 1986 and 2004. Next he performed statistical adjustments to account for the survey selection biases. The result: risk for death from obesity increases with age.
The finding jibes with countless medical studies that document how obesity takes a cumulative, even compounding toll on the human body.
"This study should put to rest the notion that it's possible to 'age out' of obesity risk, and provides a powerful counterfactual against those who say concern over obesity is overhyped," said Dr. Link, a professor of Epidemiology and Sociomedical Sciences at the Mailman School.
Going forward, Dr. Masters has set his sites on another possible reason behind the obesity paradox-that some of the older obese captured in NHIS data only put on extra weight later in life.
The researchers published the results online in the American Journal of Epidemiology.