Many real food or clean eating diets recommend steel cut oats because they are less processed and this is true, but only slightly. Starting from the same plant, the grain is cut with a sharp blade to make steel cut oats and for rolled oats it is steamed first to soften it and then rolled flat to help it cook faster.
Steel cut oats are denser and tend to be chewy or gummy when they are cooked verses their rolled sibling, and which one you prefer depends on the individual. Because they are more dense the serving size is also smaller (1/4 cup vs 1/2 cup of rolled oats)
Nutritionally the grain is exactly the same.
That’s right, I said it. They are essentially THE SAME. Same protein, same great whole grain fiber, same vitamin B benefits per serving.
I recently started making my steel cut oats in an instant pot so they are quicker and easier to make a big batch to dole out into serving sized containers for a filling breakfast. It has taken me awhile to adjust to the different texture but I do find I feel more full after a serving of steel cut oats than rolled oats.
But I do still love my overnight oats, and always use rolled oats in baking as the texture is much better for that purpose.
So the moral of the story is:
Oats are good for you, eat them!!!
However, as long as you steer clear of the sugar packed instant oats, you can pick the form you like them in best and be confident that they are still good for you.