From The New York Times, "Study Suggests Lower Mortality Risk for People Deemed to Be Overweight" by Pam Belluck:
The report on nearly three million people found that those whose B.M.I. ranked them as overweight had less risk of dying than people of normal weight. And while obese people had a greater mortality risk over all, those at the lowest obesity level (B.M.I. of 30 to 34.9) were not more likely to die than normal-weight people.