This is where the venom of pit vipers plays a dual role. Pit viper venom is a complex mixture of chemicals, but some of the main components are digestive enzymes. By injecting a large amount of venom into a prey animal the rattlesnake not only subdues it, but also begins the digestive process internally. This is very important if you are going to eat big things, because undigested food in an animals stomach can actually rot and poison the animal that ate it. Digesting your food from the inside out as well as the outside in helps keep that from happening in a rattlesnakes stomach.
Rattlesnakes are cold-blooded , as are all reptiles and therefore have a very slow metabolism.
Couple this with their preference for large food items and what you get is an animal that does not eat very often. And this is one of the keys to the life history of the eastern diamondback rattlesnake. Those of us who study the animal feel that two to three big meals each year may be enough to sustain a rattlesnake and a snake that eats five or six meals is having a great year. Ambush season might be a good name for the active part of a rattlesnakes year, but this only accounts for about six or seven months out of a snakes year. A typical year in the life of an eastern diamondback rattlesnake would end and begin in the same place, a stump hole, gopher tortoise burrow or some other underground structure.