I have tried many tools, weapons, arming and disarming cans of food in order to get the apparently hyper-precious food out of it. To no avail, unless you have the elusive can opener you cannot get the sustenance your character constantly complains for. And then you pass out.
It is sadly ironic when my character, after several hours of play, is ready to single-handedly take on the zombie apocalypse; but starves to death (unconsciousness) with a can of beans in his hands. C'mon Rocket, you experienced survival training. You know damn right you can cut a can open with a knife.