For years, standard wisdom has held that extra pounds aren’t just unattractive, they’re also unhealthy and could shorten your life. But according to new research, that may not be the case.

Anthony Jerant, professor of family and community medicine at the University of California, Davis, and his colleagues analyzed data from a six-year study involving 60,000 people and found that being overweight or even mildly obese wasn’t linked to an increased risk of premature death.

Severe obesity was — not because of the fat itself, but rather because of chronic ailments like diabetes and high blood pressure that frequently afflict those who are so overweight. However, once people with those conditions were eliminated from the data, the connection between severe obesity and a shortened life span disappeared.

And surprisingly, those with the highest risk of premature death were actually underweight people.

The researchers concede that while studies in years past have found carrying too much excess weight led to increased mortality, it’s possible that as America’s population has gotten heavier, doctors are now more aware of the associated health risks — which means those ailments are caught and treated earlier and thus have less of an impact on lifespan expectancy.

[LiveScience]