Steel-cut oats have slightly fewer calories per serving and rate lower on the glycemic index than rolled outs due to less processing. Rolled oats cook quicker than steel-cut oats and contain as much fiber, but may become mushier when cooked. However, rolled oats and steel cut oats have approximately the same amounts of protein, minerals, carbohydrates, fat and saturated fat.
Steel-cut oats, which occur when the whole grain is mechanically split, are typically chewier than rolled oats and change little in appearance and texture when cooked in water. Rolled oats are first steamed before being pressed and dried, which allows them to absorb water more easily and cook more efficiently. Quick oats are a thinner form of rolled oats that often lose their texture during preparation, while instant oats are the quickest cooking of all oat variations and are very fine in texture.
To make oatmeal using steel-cut oats, first heat a tablespoon of butter in a saucepan until it bubbles. Add 1 cup of steel-cut oats, and continue cooking for a few minutes. Then, add 4 cups of water and a pinch of salt before boiling. After the water boils, turn off the heat, and cover the oatmeal mixture. Leave the mixture overnight before reheating it in the morning. Milk and toppings such as fruit are optional additions. In total, steel-cut oats require about 30 minutes for preparation.