You may have read research that claimed that, once you hit 70, mild obesity doesn't decrease longevity but may actually be good. Re-examination of the study found serious flaws. It turn out that obesity shortens seniors lives too.
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.
The new study takes another look at the numbers and finds the earlier research flawed.
The researchers argue that past studies of longevity and obesity were biased ...
... 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,...”