The study, published in the European Heart Journal, said this group of people didn't suffer from conditions such as insulin resistance, diabetes and high cholesterol or blood pressure -- defined as metabolic syndrome -- and had a higher level of fitness, as measured by how well the heart and lungs perform, than other obese people.
"It is well known that obesity is linked to a large number of chronic diseases such as cardiovascular problems and cancer. However, there appears to be a sub-set of obese people who seem to be protected from obesity-related metabolic complications," first author Dr. Francisco Ortega of the University of Granada said in a statement.
"Until now, it was not known the extent to which these metabolically healthy but obese people are at lower risk of diseases or premature death."
The investigation took place at the University of South Carolina in Columbia under the direction of Steven Blair, who is responsible for the long-running Aerobics Center Longitudinal Study, which provided the 43,265 participants for this current analysis from 1979 to 2003.
The study found 46 percent of the obese participants were metabolically healthy and they had a 38 percent lower risk of death from any cause than their metabolically unhealthy obese peers.