A standard serving size for oatmeal is 1/2 cup of dry oats mixed with 1 cup of water or 1 cup of low-fat or skim milk. One-half cup of dry oats provides 150 calories, for a low-calorie breakfast meal. If you prepare your oatmeal with 1 cup of skim or low-fat milk, add another 83 or 102 calories, respectively.read more >>