Is cannibalism legal in the United States?

I'm just curious; this is just a thought experiment that occurred to me. I'm imagining a scenario where a husband and wife with very liberal beliefs decide that if one of them dies young, the other will eat the one's body for sustenance, naturalistically. Can they do that legally? Or would laws against desecration of a corpse impose a different moral system on them? Or alternatively, what about someone purposefully removing flesh from their body for consumption by others (or by themself)? I don't see why that wouldn't be illegal. Can a lawyer help illuminate this?