Obesity kills, giving rise to a host of fatal diseases. This much is well known. But when it comes to seniors, a slew of prominent research has reported an "obesity paradox" that says, at age 65 and older, having an elevated BMI won't shorten your lifespan, and may even extend it. A new study takes another look at the numbers, finding the earlier research flawed. The paradox was a mirage: 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 published the results online in the American Journal of Epidemiology.
The researchers 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 homea 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 65and 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," says Dr. Masters, a Robert Wood Johnson Foundation Health & 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 sur
|Contact: Timothy S. Paul|
Columbia University's Mailman School of Public Health