I'm not sure where we can go with this idea. It seems that our body is already built for survival: an energy system that takes fuel from the environment, a water-based thermal regulation system, immunity against microbes, and even a system for producing copies of ourselves, slightly changed to improve our survival chances (is that family-friendly enough for you, Jim?). To treat our bodies like an expendable resource in most situations doesn't seem like such a great approach. It's getting into Dwight K. Schrute territory. Will we be discussing self-cannibalism next?

Too bad we can't burn our waste. Otherwise that's a source of fuel.