Fiber is not a single substance. It is divided in two types, soluble and insoluble. Foods vary for these types and the amount of fiber they have. Fibers are undigested carbohydrates. Enzymes cannot break them down, that is why they cannot be absorbed in the bloodstream. But fibers give energy and are emitted from body. 

Some of the beneficial sides of fibers are mentioned below:

• Relieve from Constipation: Fiber absorbs large amount of water in the bowels, which helps in avoiding and relieving constipation.
• Prevent Heart Diseases: Foods containing soluble fibers, like oat, barley, beans have a positive effect on cholesterol, triglycerides and others, thus prevents the development of heart diseases.
• Protects from Cancer: Experts believe that Fibers protect from colon cancer. These help in preventing the harmful substances, found in some food which affect the colon.
• Other health benefits: Fibers help in reducing blood sugar level thus avoid diabetes; protect from gallstones and kidney stones.
• Weight management: Fibers help a lot in controlling weight by reducing calorie intake, sometimes slowing the hunger.

Insoluble fiber is like a sponge, which absorbs water a lot. This type of fibers is found in mainly whole grains, some fruits and etc.