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Resistant starch

Everything you need to know

Resistant starches are starch molecules that resist digestion, functioning like fiber. Studies show that they have many health benefits.

This article is based on scientific evidence, written by experts, and fact-checked by experts.
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Resistant starch: Everything to know
Last updated on December 1, 2023, and last reviewed by an expert on May 26, 2023.

Most carbohydrates in your diet are starches. But some types of starch can pass through your digestive tract without being digested. Many studies in humans show that resistant starch can have powerful health benefits.

Resistant starch: Everything to know

Starches are long chains of glucose found in grains, potatoes, and other foods. But resistant starch functions kind of like soluble fiber.

Some potential benefits include improved insulin sensitivity, lower blood sugar levels, reduced appetite, and various benefits for digestion.

Resistant starch is a very popular topic these days. Many have experimented with it and seen major improvements by adding it to their diet.

In this article

Types of resistant starch

Not all resistant starches are the same. There are 4 different types.

However, this classification is not so simple, as several types of resistant starch can co-exist in the same food.

Depending on how foods are prepared, the amount of resistant starch changes.

For example, allowing a banana to ripen (turn yellow) will degrade the resistant starches into regular ones.

Summary: There are 4 different types of resistant starch. How foods are prepared has a major effect on the ultimate amount of resistant starch.

How does resistant starch work?

The main reason resistant starch works is that it functions like soluble, fermentable fiber.

It goes through your stomach and small intestine undigested, eventually reaching your colon, feeding your friendly gut bacteria.

The bacteria in your intestine (the gut flora) outnumber the body’s cells 10 to 1 — in that respect, you’re only 10% human.

Whereas most foods feed only 10% of your cells, fermentable fibers, and resistant starches feed the other 90%.

Why is fiber good for you?
Suggested read: Why is fiber good for you?

There are hundreds of different species of bacteria in your intestine. In the past few decades, scientists have discovered that the number and type of bacteria can profoundly impact your health.

Resistant starch feeds the friendly bacteria in your intestine, positively affecting the type of bacteria and their number.

When the bacteria digest resistant starches, they form several compounds, including gases and short-chain fatty acids, most notably butyrate.

Summary: One of the main reasons resistant starch improves health is that it feeds the friendly bacteria in your intestine and increases the production of short-chain fatty acids like butyrate.

Resistant starch is a superfood for your digestive system

Eating resistant starch ends up in your large intestine, where the bacteria digest it and turn it into short-chain fatty acids.

The most important of these short-chain fatty acids is butyrate.

Butyrate is the preferred fuel of the cells that line your colon.

Therefore, resistant starch feeds the friendly bacteria and indirectly feeds the cells in your colon by increasing the amount of butyrate.

Resistant starch has several beneficial effects on your colon.

It reduces the pH level, potently reduces inflammation, and leads to several beneficial changes that should lower your risk of colorectal cancer, the fourth most common cause of cancer death worldwide.

The short-chain fatty acids that aren’t used by the cells in your colon travel to your bloodstream, liver, and the rest of your body, where they may have various beneficial effects.

Suggested read: Fiber can help you lose weight

Due to its therapeutic effects on the colon, resistant starch may aid various digestive disorders. This includes inflammatory bowel diseases like ulcerative colitis, Crohn’s disease, constipation, diverticulitis, and diarrhea.

In animal studies, resistant starch has also been shown to increase the absorption of minerals.

However, the role of butyrate in health and disease needs to be studied properly in people before any strong recommendations can be made.

Summary: By increasing the production of butyrate, resistant starch feeds the cells of your colon and leads to various improvements in the function of your digestive system.

Health benefits of resistant starch

Resistant starch has various benefits for metabolic health.

Several studies show that it can improve insulin sensitivity — the responsiveness of your body’s cells to insulin.

Resistant starch is also very effective at lowering blood sugar levels after meals.

It has a second meal effect, meaning that eating resistant starch with breakfast will also lower your blood sugar spike at lunch.

The effect on glucose and insulin metabolism is very impressive. Some studies have found a 33–50% improvement in insulin sensitivity after four weeks of consuming 15–30 grams daily.

The importance of insulin sensitivity cannot be stressed enough.

Low insulin sensitivity (insulin resistance) is a major risk factor for several serious diseases, including metabolic syndrome, type 2 diabetes, obesity, heart disease, and Alzheimer’s.

By improving insulin sensitivity and lowering blood sugar, resistant starch may help you avoid chronic disease and improve your quality of life.

However, not all studies agree that resistant starch has these beneficial effects. It depends on the individual, the dose, and the resistant starch type.

Summary: Many studies show that resistant starch improves insulin sensitivity and lowers blood sugar levels, especially after meals.

Resistant starch may aid weight loss by improving satiety

Resistant starch has fewer calories than regular starch — two vs. four per gram.

Suggested read: Bananas: Nutrition facts, vitamins, and health benefits

The higher the resistant starches content in a food, the fewer calories it will have.

Several studies show that soluble fiber supplements can contribute to weight loss by increasing feelings of fullness and reducing appetite.

Resistant starch appears to have the same effect. Adding resistant starch to meals increases feelings of fullness and makes people eat fewer calories.

A few animal studies show that resistant starch can cause weight loss, but this effect hasn’t been studied properly in people.

Summary: Resistant starch has fewer calories than regular starch and may increase feelings of fullness and help people eat less.

How to add resistant starches to your diet

There are two ways to add resistant starches to your diet: get them from foods or take a supplement.

Several commonly consumed foods are high in resistant starch.

This includes raw potatoes, cooked and then cooled potatoes, green bananas, various legumes, cashews, and raw oats.

As you can see, these are all high-carb foods, making them out of the question if you’re currently on a very low-carb diet.

However, you can eat some on a low-carb diet with carbs in the 50–150-gram range.

That being said, you can add resistant starch to your diet without adding any digestible carbohydrates. For this purpose, many people have recommended supplements, such as raw potato starch.

Raw potato starch contains about 8 grams of resistant starch per tablespoon and almost no usable carbohydrates.

What’s more, it’s very cheap.

It tastes bland and can be added to your diet in various ways, such as by sprinkling it on your food, mixing it in water, or putting it in smoothies.

Four tablespoons of raw potato starch should provide 32 grams of resistant starch. Starting slowly and working your way up is important, as too much too soon can cause flatulence and discomfort.

There’s no point in taking much more than that since excess amounts seem to pass through your body when you reach 50–60 grams per day.

It may take 2–4 weeks for the production of short-chain fatty acids to increase and for you to notice all the benefits — so be patient.


If you’re trying to break a weight loss plateau, have high blood sugar or digestive problems, or are simply in the mood for some self-experimentation, then trying out resistant starch seems like a good idea.

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