Snakes do not eat every day like we do, since they are cold-blooded. That means that they do not make their own body heat internally, from the calories they get in food, the way that mammals do, and since they do not need anywhere near as many calories to maintain that body heat, they do not need to eat nearly as often as warm-blooded animals like mammals and birds. Most snakes the size of a Grass Snake will eat one or two meals per WEEK if they are lucky enough to catch something. Really large snakes, like Boas and many Pythons, only need to eat once every month or so, and can go for several months without eating.