Dietary Fiber is an indigestible complex carbohydrate found in plants. Fiber is not a single food or substance. Fiber in it's self has no calories because the body cannot absorb it. Therefore, high fiber foods low in fat are low in calories such as fruits and vegetables. Fiber can be divided into two categories according to their physical characteristics and effects on the body: Water insoluble and water soluble. Each form functions differently and provides different health benefits. Insoluble fibers, such as cellulose, hemicellulose and lignin, do not dissolve in water. Soluble fibers, such as gum and pectin, do dissolve in water.If you have been doctoring your bran in hopes of getting fiber's benefits, what you are mostly getting are larger, softer stools, This kind of fiber “bulks up” waste and moves it through the colon more rapidly, preventing constipation and possibly colon cancer. The trickiest accomplishments of fiber may lie with the stickiest kinds called gums and pectins, as they may keep cholesterol under control by removing bile acids that digest fat. The same types of fiber may regulate blood sugar as well. This is accomplished by coating the gut's lining and delaying stomach emptying. As a result, this can slow sugar absorption after a meal and may reduce the amount of insulin needed. Fiber is a weight watchers dream since fiber called cellulose and hemicellulose take up space in the stomach, making us feel full, therefore food intake is less.