Lobstrosity Meat is the only food avaliable directly on the Western Sea. In The Dark Tower II: The Drawing of the Three, this is essentially the only food Roland Deschain, Eddie Dean, and Odetta Holmes eat. This goes on for weeks.
The meat comes from the Lobstrosities, and Roland is disquisted by them, fearing he may eat the fingers or toe they took from him, although Eddie, at the heat of his anger, takes satisfation in this thought.
According to Roland initally, the meat is not the best he had, and a bit rough.