Some foods promote a feeling of 'fullness' quicker than others. High fiber content is often found in such foods and eating high fiber foods can aid in safe weight loss. Due to its chemical makeup, fiber is classified as a carbohydrate; however, it is unlike other carbohydrates in that it is an indigestible nutrient. Even though each gram of fiber contains four calories, these calories will remain undigested and will not be absorbed. Therefore, if you were to consume 300 calories of red beans (a food in which nearly one-third of the caloric content is from fiber), approximately 100 of these calories would pass through your intestinal tract undigested.