Dietary fiber is not absorbed by the body but it absorbs water and becomes a gel like blob. It can absorb water in the digestive system and promotes bowel movement. High fiber usually takes more time to eat and the body has more time to register that you are not hungry. It would also feel that the meal you have eaten is still felt so you don’t feel hungry for a longer period. Dietary fiber like glucomannan also has fewer calories but the same amount of food. It would help in losing some of the weight with almost the same amount of food intake.