What carbohydrate is indigestible for humans?

Dietary fiber is another kind of complex carbohydrate. Though it does not act as a source of energy for the body it provides many other positive benefits. Fiber is classified by nutritionists as either insoluble fiber or soluble fiber. This is based on whether it dissolves in water. Both insoluble and soluble fibers are incapable of being broken down by the body's digestive enzymes. For this reason, fiber adds no additional calories to your diet and it cannot be converted to glucose.