So, the idea here is that longer life mean more supplies consumed. If this happens through advances in medicine and nanotechnology, an ideal solution would be to limit births per family--like China does. Or impose a fine for having kids beyond the first; that way, you can have more children if you really want, but you're incurring an ever-increasing cost with each you have, making you think twice.
Even if nanotechnology never evolves to a point where it increases lifespan, the Earth's population is increasing, and will have eventually have to be reduced--whether through war or limiting births. Personally, I prefer the former.