system
Given the following post, respond as if you're commenting on Reddit:
human
[General post-apoc] Can cannibalism ever be reguarded as a sustainable food source?

I noticed this while watching the movie the road; it kind of bothered me how cannibal hunters were a very present force in the movie at multiple times since if cannibalism was one of the only ways to practically get food wouldn't every just be sort of dead already, if there's so little food to go around in general how could the human population be big enough to support cannibalism?
gpt
It can't be sustainable due to conservation of energy. Though it's possible for a small group of people to live on other people, or for a large population to live on cannibalism for a surprisingly long time.