Then the hunger goes away even while your body continues to burn excess stored fat Calories for fuel. Obviously, in the ordinary metabolic sense of the term, fiber is not a nutrient at all. Therefore, since fiber comes from food and your body needs fiber for an important function, it tends to treat fiber just like any ordinary biochemical nutrient - it triggers hunger and eating whenever it needs more. Most scientists and nutritionists have accepted that the body needs between 20 and 30 grams of fiber per day for optimal elimination of waste. Many people routinely get much less fiber than this.
Animal foods have no natural fiber.
Highly refined plant foods often have had much of their natural fiber removed. Since many people eat most of their food from these sources, they may easily be getting much less fiber than their bodies want. This sets up the standard situation in which their bodies may often be triggering hunger and eating and unnecessary Calorie intake just to get more of the fiber that they need. Naturally, over time this tends to put on those unwanted pounds. Equally naturally, in order to reverse the process, you need to take conscious control of your eating choices and push them back in the direction of foods with more fiber and fewer Calories.