Diets high in fiber help normalize bowel movements, lower blood cholesterol, aid in blood sugar control and help control hunger, according to the Mayo Clinic. Whole grains are also naturally low in fat and high in fiber. Grains like oats and barley contain high amounts of soluble fiber. Soluble fiber prevents the absorption of cholesterol helping to lower blood cholesterol levels. Other grains high in fiber include whole-wheat spaghetti, bran flakes, popcorn, brown rice and whole-wheat bread.