The best fiber to use for weight loss is water-soluble fiber. Examples of water-soluble are psyllium, gluconmannan, guar gum, and pectin. When taken with water before meals or with meals, these fiber sources bind to the water in the stomach to form a gelatinous mass that makes you feel full. As a result, you will be less likely to overeat.
The benefits of fiber go well beyond this mechanical effect. Fiber supplements have been shown to enhance blood sugar control and insulin effects, as well as reduce the number of calories absorbed by the body. In clinical studies demonstrating weight loss, fiber supplements were shown to reduce the number of calories absorbed by 30-180 calories/day. This reduction in calories may not seem like much, but over the course of a year it would add up to three to eighteen pounds.
In addition to weight loss, fiber supplementation promotes good health. Studies have shown these very same water soluble fiber sources to reduce the risk of heart disease by lowering cholesterol levels and lowering blood pressure, reduce the risk for various cancer including colon, rectal, and pancreatic cancer, reduce blood sugar levels in diabetes, promote proper bowel movement function, and help with peptic ulcers.
There are many fiber supplements to choose from. I recommend one that is rich in water-soluble fiber and avoid products containing added sugar or other sweeteners. One other very important recommendation is to be sure to drink adequate amount of water when taking and fiber supplement.
Remember to start with a small dosage and increase gradually. Water soluble fibers are fermented by intestinal flora. As a result, gas and bloating can be a problem. If you are not used to a high fiber diet, an increase in dietary fiber can lead to increased flatulence and abdominal pain. Start out with a dosage of 1-2 grams before or with meals and gradually increase the dosage. How much weight will you loose? It really depends on how much you weigh, you should lose 50-100% more weight by supplementing you diet with fiber than by dietary restriction alone.
Caution: individuals with a disorder of esophagus should not take fiber in pill as it can expand in the esophagus and create obstruction in the gastrointestinal tract.