This is just the reverse of the well-known fact that animals such as rats and monkeys on a subsistance diet have significantly increased lifespans. Of course I've heard it said that a person on such a diet would probably rather be dead.
A friend of mine was on the calorie-reduction (CR) diet -- he was eating 30% fewer calories than typical diets. He was rail-thin. I gather an unexpected side-effect of a CR diet is having to explain to people that you are healthy, that you're so thin because you're on a special diet.