Undiagnosed illnesses that causes one to be malnourished are often responsible for cannibalistic dreams. I had these nightmares involving cannibalism after being sick with diabetes for 5 years before it was diagnosed. High blood sugar doesn't mean a person has lots of energy. It means one's blood is too thick to get into tiny microscopic cells that are made to receive nutrients out of food. So the body is "starving"; as organs and systems begin to starve and break down, one might have very physical, visceral nightmares concerning, especially--the body. One of mine involved a giant woman, naked on her hands and knees beside the highway on which I was driving; she was eating raw steak. One of mine involved the Larry Flynt style meat grinder with a woman going in and coming out as toppings for my pizza--raw and ground. One involved a woman wearing a dress made out of cabbage chasing me. One was a dream in which I shot up thick green kool-aid with a needle. Turns out I had been diabetic for 5 years without knowing it. Once the sugar was stabilized, the dreams stopped. So, as the first guy said, get a doctor, just in case.