dumb for several reasons:
works in animals, typically, by postponing adolescence, which makes sense. the body needs nutrients to progress to that stage, and evolutionarily speaking, the point of existence is to get to a stage where one can procreate. therefore when it takes longer, there is some mechanism that allows the organism to live longer in order to procreate.
this has never been proven in humans, and never will.
sure, they can do a study on adults, but i bet it is inconclusive. they would have to do a double blind study on children, starving some of them.
beyond that, who wants to live 5 or 10 years longer while being a ultra-skinny faggot who doesn't enjoy food in any way? a more effective way to prolong the lives of future generations is to put age limits on procreation. within a few generations we would live significantly longer.