Fiber is technically a carbohydrate, except you don't digest it. Fiber has a key role in helping your body fight diseases. Some benifits of fiber are that it keeps your digestive system running smoothly and elminates waste often. There are two basic kinds of fiber. Soluble fiber, which disolves in water soaking up fluid in your stomach and small intestine. It also absorbs fats and cholesterol. The other kind of fiber moves through your body cleaning up substances that you have eaten that may be harmful. It also speeds up the time it takes for food to get from the entrance of your digestive track to the other. With enough fiber, you can cut that time in half.