The exclusion of nursing home residents should cast serious doubt on studies showing a positive relationship between obesity and lifespan, according to a new report.

Controversial studies have proposed recently that elevated body mass doesn’t lead to bad health outcomes after a certain age. Some proponents of the “obesity paradox” have said the extra padding cushions falls and provides energy that can fuel the body during illness, extending the lifespan of obese seniors.

However, studies that were based on National Health Interview Survey data are flawed, according to researchers from Columbia University’s Mailman School of Public Health and the University of Texas. The NIH surveys did not include seniors living in nursing homes or institutional settings, skewing the results in favor of healthier people, the researchers say.

Looking at NHIS data along with information from the National Death Index, the Columbia and Texas researchers found obese older people have an overall greater risk of dying. Obese adults are defined as those who have a 30 or higher on the Body Mass Index scale.

“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,” says study author Bruce Link, Ph.D., professor of epidemiology and sociomedical sciences at the Mailman School.

The results are published in the online edition of the American Journal of Epidemiology.