When thinking of a healthy, hearty breakfast, a steaming hot bowl of oats might come to mind. This cereal grain is commonly rolled or crushed to make oatmeal or ground into a fine flour for use in baking. Oats are also used in dry pet food and as livestock feed to nourish animals like horses, cattle and sheep. They're a fiber-rich carb that's low in fat and high in protein, vitamins and minerals.
There are several types to choose from, including rolled, steel-cut and quick-cooking oats, and they differ in their nutrient profile and processing methods. This article explains the key differences between rolled, steel-cut and quick oats so that you can decide which one makes the most sense for your diet and lifestyle.
Oat groats are oat kernels that have had the hulls removed. The hulls are the tough outer shell that protects the seed of the oat plant. Steel-cut, rolled and quick oats all start out as oat groats. Oat groats intended for human consumption are exposed to heat and moisture to make them more shelf-stable. The oat groats are then processed in different ways to create either steel-cut, rolled or quick oats, all of which have distinct characteristics. 
Also known as Irish oatmeal, steel-cut oats are most closely related to the original, unprocessed oat groat. To produce steel-cut oats, the groats are chopped into pieces with large steel blades. Steel cut oats have a coarser, chewier texture and nuttier flavor than rolled or quick oats. They also take longer to prepare, with average cooking times varying 15-30 minutes. However, you can soak steel-cut oats beforehand to reduce the cooking time.
Rolled oats, or old-fashioned oats, are oat groats that have gone through a steaming and flattening process. They have a milder flavor and softer texture and take much less time to make than steel-cut oats, as they have been partially cooked. A bowl of rolled oats takes 2-5 minutes to prepare. Rolled oats can also be added to goods like cookies, cakes, muffins and bread.
Quick oats or quick-cooking oats are rolled oats that go through further processing to decrease cooking time. They're partially cooked by steaming and then rolled even thinner than old-fashioned oats. They cook within a few minutes, have a mild flavor and soft, mushy texture. Quick oats are not the same as instant, packaged oats that sometimes contain other ingredients like skim milk powder, sugar and flavoring.
SUMMARY
Steel-cut oats have a chewy texture and nutty flavor, while rolled and instant oats are milder with a softer texture. Steel-cut oats are the least processed of the three. 
Oats have many health benefits.
These fiber-rich whole grains are a good source of protein and packed with vitamins, minerals and antioxidants. Plus, they are gluten-free, so they make a great choice for those with celiac disease or an intolerance to gluten.
While oats are naturally gluten-free, people with celiac disease should choose varieties that are certified gluten-free to avoid those that may have been contaminated with gluten during processing.
Just a half cup (40 grams) of dry, rolled oats contains:
Calories: 154
Protein: 6 grams
Fat: 3 grams
Carbs: 28 grams
Fiber: 4 grams
Thiamin (B1): 13% of the RDI
Iron: 10% of the RDI
Magnesium: 14% of the RDI
Phosphorus: 17% of the RDI
Zinc: 10% of the RDI
Copper: 8% of the RDI
Manganese: 74% of the RDI
Selenium: 17% of the RDI
Oats are also loaded with beneficial compounds, including antioxidants and beta-glucan, a type of soluble fiber linked to health benefits.
For example, the beta-glucan found in oats is effective at lowering both bad LDL and total cholesterol, which may help keep your heart healthy.
A recent study in 80 people with high cholesterol found that consuming 70 grams of oats for 28 days led to an 8% reduction in total cholesterol and an 11% reduction in bad LDL cholesterol. Additionally, oats have been shown to aid weight loss and stabilize blood sugar levels.
The beta-glucan in oats helps slow digestion, leading to an increased sense of fullness and more gradual spike in blood sugar.
In a study of 298 people with type 2 diabetes, those who consumed 100 grams of oats per day experienced significant reductions in fasting and post-meal blood sugar, compared to those who did not consume oats.
Plus, the group that ate 100 grams of oats daily had a significantly greater decrease in body weight, which the researchers related to their high amount of beta-glucan.
SUMMARY
Oats are highly nutritious and have been associated with a number of health benefits. Eating them may help lower cholesterol, decrease blood sugar levels and help with weight loss. 
The variety of oats on the market can make it difficult for consumers to determine the healthiest option. The chart below compares the nutritional differences between 2 ounces (56 grams) of rolled, steel-cut and quick oats.
Rolled Oats Steel-Cut Oats Quick Oats Calories 212 208 208 Carbs 39 g 37 g 38 g Protein 7 g 9 g 8 g Fat 4 g 4 g 4 g Fiber 5 g 6 g 5 g Sugar 1 g 0 g 1 g As you can see, the variations between these three oat varieties are slight.
Furthermore, a proper study with statistical tests is needed to confirm these differences. That said, the data available indicates that there may be some distinctions between steel-cut, rolled and quick oats.
Since steel-cut oats are the least processed of the three, they contain the most fiber but only by a small difference.
The fiber found in steel-cut oats is beneficial for digestive health, fueling the good bacteria in the intestines and promoting regular bowel movements.
However, it's important to note that all oats are an excellent source of fiber, and the variation in fiber content between steel-cut, rolled and quick oats is slight. 
Steel-Cut Oats May Have a Lower Glycemic Index
Steel-cut oats may have a lower glycemic index than rolled or quick oats, meaning the body digests and absorbs them more slowly, leading to a slower rise in blood sugar.
Foods with a high glycemic index cause more rapid spikes in blood sugar, while foods lower on the glycemic index provide a slower release of energy and can help stabilize blood sugar.
For this reason, steel cut oats may be the best choice for those looking for better control of their blood sugar.
SUMMARY
Steel cuts oats are slightly higher in fiber than rolled and quick oats. They also have the lowest glycemic index of the three types of oats, potentially making them the best choice for blood sugar control.
Although steel-cut oats contain a bit more fiber and are lower on the glycemic index, don't discount rolled and quick oats.
All three types are highly nutritious and excellent sources of fiber, plant-based protein, vitamins, minerals and antioxidants. The most important thing is to choose an oatmeal that fits best with your lifestyle. 
When determining the best type of oatmeal to stock your pantry with, it's important to keep your personal preferences in mind. The chewy texture and nutty flavor of steel-cut oats may be delicious to some but too hearty for others.
