A new analysis has found that body weight does not necessarily correspond to longevity and that those carrying extra pounds outlive their thinner peers. The study also found that those who were slightly to moderately overweight at ages 65 and older had a lower mortality rate.

The report in the Journal of the American Medical Association was not the first to make the connection between weight and lifespan, but is the most intensive with data from nearly 100 studies and three million people, researchers say.

In an editorial coinciding with the paper, Steven Heymsfield, M.D., executive director of the Pennington Biomedical Research Center in Louisiana, wrote that overweight people whose indicators such as cholesterol “are in the abnormal range, then that weight is affecting you.” He added that if indicators are normal, there’s no need to “go on a crash diet.”

Experts suggested that concepts of fat and the body mass index (BMI), which provides a ratio of height to weight should be revised. However, those in the highest obesity categories of BMI remained at high risk.

One possible factor for the findings is that the overweight or somewhat obese are already being treated for weight-associated conditions such as high cholesterol or diabetes. Some suggested fat could be protective in some cases. But experts were quick to say that individuals should not try to gain excessive weight to live longer.