When digesting sometimes large food items, snakes benefit from a digestive system that can transition from dormant to fully operational very quickly. According to the BBC, when a snake eats a large prey item, its stomach and intestines expand rapidly, its metabolic rate goes up, and it increases the amount of digestive enzymes that are produced.
Even with the digestive adaptations that snakes possess, it can take them a very long time to digest their food. During this time, the snake's midsection often bloats dramatically for several days. During this time, many snakes bask for prolonged periods in an effort to speed up digestion. After the bulk of the food has been digested, the snake defecates the indigestible portions of the meal, such as hair, fingernails and scales.
The nearly 3,500 living snake species exhibit a wide variety of lifestyles and food habits. While some species, notably pythons, anacondas and boas, are capable of eating very large prey at infrequent intervals, many other species consume food of more modest dimensions. Such snakes usually eat more regularly than those that predate on large animals. For example, garter snakes prey on animals, such as worms, fish and frogs, which they eat on a regular basis. This contrasts with large constrictors that may only eat a few times per year.