I know that this description sounds a lot like “Motel Hell,” but I am positive it is not. I saw this black-and-white movie in the mid-70s, but it was an old movie even then. A young woman goes to stay at a farm or a resort (to gain weight or lose weight, maybe?), and realizes that the caretakers are butchering people for meat. Somehow, she defeats them, and the final scene is of the freezer or meat locker, where we see the heads of the two dead caretakers. At the very last second, one of the heads winks at us.