And some whole grain cereals are loaded with unnecessary sugar. 1  Â½ cup Fiber One = 14 grams of fiber. 2  1 cup Raisin Bran = 7.5 grams of fiber. 3  1 cup Frosted Shredded Wheat Spoon Size = 5 grams.  1 cup Quaker Squares Baked in Cinnamon = 5 1  grams. Â¾ cup cooked oatmeal = 3 grams. *Recommended serving sizes.