Researchers looked at data on nearly three million adults around the world. They looked at body mass index, a measurement of weight in relation to height, to the risk of death.
The study found people slightly overweight had a six percent lower risk of dying.
But, researchers say it's not an excuse to pack on the pounds. The study also found that obese people had more than triple the risk of dying.
And the research looked at only death, not chronic medical conditions.
The study is published in the latest issue of the Journal of the American Medical Association.
