Researchers here argue that flawed data led to some scientists to conclude that being overweight is less harmful to long-term health than it in fact is:
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.
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 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."