What to Know About Resistant Starches

Reviewed by Christine Mikstas, RD, LD on September 01, 2021

Many people have added resistant starches to their diets due to the health benefits they provide. Resistant starch is a type of nutrient that can boost digestion, prevent diseases, and promote weight loss. While most starches are digested and broken down, resistant starch will pass through you unchanged.

What Is Resistant Starch?

Resistant starch is a type of carbohydrate that doesn’t get digested in your small intestine. Instead, it ferments in your large intestine and feeds beneficial gut bacteria.

This type of starch provides numerous health benefits and has fewer calories than regular starch. Resistant starches have only two and a half calories per gram, while regular starches contain four calories per gram. As such, it’s a great addition to your diet if you’re looking to lose or maintain weight.

The Four Types of Resistant Starches

Type 1. Type 1 starches are found in partially milled seeds and grains, as well as in some dense starchy foods. This type of starch is stuck within fibrous cell walls. So it’s not digested.

Type 2. These are found in starchy foods like raw bananas and potatoes. Type 2 starches are indigestible because they are compact, which makes it hard for digestive enzymes to break them down.

Type 3. This is the most resistant type of starch. Type 3 starches are found in foods that have been cooked and cooled, such as bread and cornflakes. The process of cooling turns some of the starches into resistant starches.

Type 4. This type of starch is man-made and is usually found in bread and cakes.

Benefits of Resistant Starch

Boosts gut health. Normal starches are broken down into glucose when digested. Resistant starches do not break down. As resistant starch ferments in your large intestine, more good bacteria is created, boosting your overall gut health.

This increase in good bacteria will lead to decreased levels of constipation, lower cholesterol levels, and a reduced chance of gas pains.

Keeps your colon healthy. The good bacteria in your large intestine acts to turn resistant starch into short-chain fatty acids, the most important of which is butyrate. 

Butyrate is the preferred energy source of your colon cells. It can:

  • Reduce the pH level of your colon.
  • Reduce inflammation.
  • Reduce the chances of developing colorectal cancer.

Encourages high levels of insulin sensitivity. Resistant starches can improve your body's ability to respond to insulin. The higher your insulin sensitivity, the better your body will be able to handle high blood sugar. This means you’ll have a lower chance of developing conditions such as type 2 diabetes.‌‌

Lowers risks for certain conditions. Resistant starches can increase your insulin sensitivity, which in turn may lower your chances of getting certain conditions, such as Alzheimer's disease and mild cognitive impairment (MCI).

Encourages weight loss. Since resistant starches are harder to digest, your body will use up more energy trying to break them down. This means you won’t get hungry as quickly and as a result you’ll be eating less.

Adding Resistant Starch to Your Diet

The following foods are particularly high in resistant starch:

  • Rice or potatoes that have been cooked and cooled
  • Whole grains such as barley and oats
  • Plantains
  • Green bananas (not yellow or ripe bananas, which have regular starch)

Here are some ways you can add more resistant starches to your diet:

  • Adding lentils to a soup or salad.
  • Using uncooked oats to make overnight oats, which consists of soaking the oats in milk or yogurt. Overnight oats have more resistant starch than cooked oatmeal.
  • Cooking potatoes, pasta, beans, and rice and allowing them to cool in the refrigerator before eating. Reheating these items after they have cooled off won’t affect the levels of resistant starch.

Flours such as green banana flour, cassava flour, plantain flour, or potato starch are good substitutes for wheat flour. They do contain high amounts of resistant starch, but only when consumed raw such as sprinkling on food or adding it to water or smoothies. The resistant starch content is lost when it is heated such as when used for baking or cooking.

Show Sources


American Journal of Physiology Gastrointestinal and Liver Physiology: “Butyrate suppresses colonic inflammation through HDAC1-dependent Fas upregulation and Fas-mediated apoptosis of T cells.”

Cell Metabolism: “The microbiome and butyrate regulate energy metabolism and autophagy in the mammalian colon.”

Centers for Disease Control and Prevention: “Insulin Resistance and Diabetes.”

Comprehensive Reviews in Food Science and Food Safety: “Resistant Starch–A Review.”

Critical Reviews in Food Science and Nutrition: “Resistant starch and energy balance: impact on weight loss and maintenance.”

Mayo Clinic: “Diabetes and Alzheimer's linked.”

Microbiome: “Resistant starch can improve insulin sensitivity independently of the gut microbiota.”

Nutrition and Cancer: “Comparative Effects of Three Resistant Starch Preparations on Transit Time and Short-Chain Fatty Acid Production in Rats.”

The American Journal of Clinical Nutrition: “Effects of resistant starch on the colon in healthy volunteers: possible implications for cancer prevention,” “Insulin-sensitizing effects of dietary resistant starch and effects on skeletal muscle and adipose tissue metabolism.”

The Johns Hopkins Patient Guide to Diabetes: “What Is Resistant Starch?”

World Journal of Gastroenterology: “Potential beneficial effects of butyrate in intestinal and extraintestinal diseases.”

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