Foods rich in soluble fiber are important to add to your daily diet. Soluble fiber gets converted into fatty acids and are then used as an energy source for the body. Once dissolved into a liquid in the body, a gel is formed in the gut that "slows the emptying of the stomach, leading to a prolonged feeling of fullness," Lee told POPSUGAR. She also added that fiber can be found in a wide variety of foods such as oats, barley, and rye, fruits that contain pectin, like apples, plums, and oranges, root vegetables, like carrots and potatoes, and legumes, such as soybeans, kidney beans, and lentils.