The Complete Guide to Resistant Starch + 8 Benefits


If you want to know what resistant starch is, where it comes from, what it does, how you can benefit from it, and why it is important, then you want to read this article. 


Potatoes when cooked and cooled become loaded with resistant starch.

In the current nutrition climate, carbohydrates are under attack from all fronts. They’re blamed for just about everything horrific that can happen to you from a physiological and physique perspective, and even more recently, they are even some who state that carbs aren’t even all that useful for athletic performance, which is just laughable by the way.

Amidst this damning of all things carbohydrate-related emerges a type of carb considered by even the most diehard carbophobe or keto zealot to be useful. It might even be “healthy”, though don’t say that too loud, or the keto klansmen might hunt you down.

This beneficial carbohydrate we’re referring to is none other than resistant starch.

There’s a pretty good chance you’ve never heard of this type of carbohydrate, but sit back, relax, and enjoy your cup of bulletproof coffee (or Ritual AM) as we delve into all things resistant starch.

What is Resistant Starch?

Most of you reading this are familiar with the concept of starches. They’re abundantly found in foods like potatoes, sweet potatoes, and pasta.

What starches actually are, are a plant’s form of stored energy.[1] In a sense, starch is to plants what glycogen is to humans -- the stored form of glucose.

Plants produce starch from glucose to create a supply of energy for those times when food is scarce. Tubers (i.e. sweet potatoes), roots, and seeds typically contain higher amounts of starch as they serve as the “fuel reservoir” for the infant plant during its early phases of growth.[2]

Similarly, when we eat food, our liver and muscles store glucose in the form of glycogen to be utilized when needed for activity and intense exercise.

In plants, starch can be found in two forms: amylose and amylopectin. Between these two, glycogen is more similar to amylopectin, since the sugar molecules in glycogen and amylopectin are highly branched, while amylose has a strictly linear structure.

Now, here’s where resistant starch enters the picture...

Resistant starch is defined as a “portion of starch that cannot be digested by amylases in the small intestine and passes to the colon to be fermented by microbiota.”[3]

In other words, resistant starch is a type of fiber.

Our bodies can’t digest it, but our gut bacteria use it for fodder. This is why “resistant starch” is called resistant -- it resists breakdown in the stomach and small intestine. Once it reaches the large intestine, gut bacteria use it for food and ferment it into short-chain fatty acids, or SCFAs for short.[3]

Types of Resistant Starch

Now, the idea of a resistant starch seems pretty straightforward -- it’s part of a starch molecule that we can’t digest. But as things usually go, it’s not that simple.

There’s not just one type of resistant starch, but four (or five) different types depending on which studies you read.[3,4]




Type I

Physically inaccessible starch

Coarsely ground or whole-kernel grains

Type II

Granular starch with the B- or C-polymorph

High-amylose maize starch, raw potato, raw banana starch

Type III

Retrograded starch

Cooked and cooled starchy foods

Type IV

Chemically modified starches (man-made)

Cross-linked starch and octenyl succinate starch

Type V

Amylose-lipid complex

Stearic acid-complexed high-amylose starch

TABLE 1: Types of resistant starches[3]

If that’s not enough to muddy up the waters concerning resistant starch, consider this -- different types of resistant starch can be present simultaneously in the same food, and on top of that, how you cook your food also impacts to the amount of resistant starch changes.

For example, if you purchase a green banana at the store on Sunday and allow it to ripen, the resistant starches present when the banana is green turn into regular starches as the banana becomes more and more yellow.

Furthermore, researchers haven’t come to a consensus on how to quantify the amount of resistant starch in each food. Depending on which paper your read, you’re going to find that the same food can have vastly different amounts of resistant starch.

The final “kink” with the various types of resistant starch is that each resistant starch has a different impact on your body’s glycemic response, meaning each will affect blood sugar levels a tad bit differently.[5]

Now, we’re not here to get bogged down in the minutiae of how each resistant starch impacts your blood sugar levels. We’re more concerned with the big picture of what resistant starches do and what, if any, benefits they have to offer.


What Does Resistant Starch Do?

Resistant starch primarily functions like a soluble, fermentable fiber. Like other soluble fibers (i.e. the kind found in black beans and oats), it passes through your stomach and small intestine undigested. When it reaches your colon, the “good” gut-friendly bacteria feast on it.[6]

As you probably know, the human microbiome has received an inordinate amount of attention lately with new studies emerging weekly it seems. The is due to a variety of reasons including new links that have been found between the gut’s impact on mental health[11], the gut’s impact on physical performance[10], and the simple fact that our gut flora (bacteria in our gut) outnumber the cells in our body 10 to 1.[7]

Another way of looking at it is this. Of all the food we eat, only 10% of our cells are really nourished by it. The other 90% feeds on the resistant starches and fermentable fibers we consume on a daily basis.[8,9]

When you look at it that way, it might be worthwhile to start upping your intake of fiber-rich foods.

Research has shown that resistant starch feeds the “good” gut bacteria, which not only helps increase the number of bacteria, but also increase the diversity as well.[12,13]

As the gut bacteria digest these resistant starches, they form a number of compounds, including an assortment of gases (methane, hydrogen, carbon dioxide) as well as short-chain fatty acids (acetate, propionate, butyrate, and valerate).[14,15] Smaller amounts of organic acids (lactate, succinate, and formate), alcohols (methanol and ethanol) and, branched short-chain fatty acids (isobutyrate and isovalerate) are also generated.

Out of all of these compounds, the one we’re most interested in is butyrate.

Meet butyrate -- the preferred energy source for the cells in our colon

Butyrate is the preferred energy source of the cells lining our colon, and it has been shown to impart several other benefits including:

  • Boosting metabolism
  • Lowering inflammation
  • Improving resistance to stress

  • Furthermore, butyrate also promotes a normal phenotype for cells of our colon, which may serve as a measure of protection from certain diseases such as colorectal cancer.[16] And, compared to other soluble fibers, resistant starch is superior for ramping up butyrate production[17], which makes consumption of resistant starch a priority if you’re trying to improve gut health or rebuild your microbiome following a run of antibiotics.

    Now, let’s take a look at some of the other benefits that come with resistant starch, and why they’re so popular in the low/no-carb communities.

    Benefits of Resistant Starch

    Numerous studies have been conducted on the effects of resistant starch intake, and from those studies, researchers have found several positive correlations associated with resistant starch intake, including:

    Lowers Blood Glucose

    Sky-high blood sugar levels and insulin resistance are an increasingly common occurrence these days in both adults and children. These conditions are strongly associated with a host of diseases, including obesity, type 2 diabetes, and metabolic syndrome.  

    Several studies have note that resistant starch intake may improve insulin sensitivity (independent of gut bacteria)[19], and decrease postprandial (after a meal) blood glucose levels.[20]

    One particularly interesting study noted that consuming 15 and 30 grams per day of resistant starch led to better insulin sensitivity in overweight and obese men, equivalent to could be expected with a 10% drop in body weight.[21]

    Even more noteworthy, is that resistant starch exerts something called a “second meal effect”. What this means, is that not only does resistant starch lower blood sugar response following the meal it is consumed, but also lowers blood glucose and insulin levels in the next meal as well![22]

    Improves Gut Health

    As we mentioned above, consuming resistant starch leads to increased levels of butyrate. This short-chain fatty acid serves as a powerful anti-inflammatory agent for the cells lining our colon and fortify the integrity of our gut by decreasing intestinal permeability (a.k.a. “leaky gut”). This helps prevent various toxins and other ne’er-do-wells out of the bloodstream, helping keep us free from illness and disease.[23,24]  

    Additional research has noted that resistant starch intake is also associated with a reduced risk of colorectal cancer. Researchers believe this is due to a few different mechanisms including[25]:

  • Favorable changes in gene expression
  • Protection from DNA damage
  • Up-regulation of apoptosis (programmed cell death) of cancerous and precancerous cells

  • In the instance, the short-chain fatty acids resulting from fermentation of resistant starch aren’t immediately needed by the cells of the colon, they enter the bloodstream where they can impart their anti-inflammatory effects in other regions of the body.

    May Aid Weight Loss

    One of the main reasons resistant starch has gained such immense popularity, especially in the fad diet world, is due to some research indicating it may boost weight loss.

    How is that?

    For starters, resistant starch has fewer calories per gram than regular starch. Resistant starch contains two calories per gram while regular starch contains four calories per gram. So, the greater amount of resistant starch a food has, the few calories it will contain.

    Second, resistant starch serves as a soluble fiber. Various studies show that soluble fiber intake helps reduce appetite and increase satiety.[25,26] Additional research has noted that incorporating resistant starch into meals exerts the same effect, leading people to eat fewer calories.[27,28]

    And, since weight loss ultimately boils down to calories in vs calories out, this aids to weight loss.

    Additional Benefits

    A few other notable benefits associated with the consumption of resistant starches includes[19]:

  • Reduced plasma cholesterol levels
  • Improved triglyceride concentrations
  • Increased satiety
  • Decreased fat storage
  • Enhanced hydration

  • Resistant Starch Content of Common Foods

    For the individual eating a well rounded diet, high in fruits, vegetables, lean proteins, and whole grains, on average their gut bacteria may be exposed to as much as 20 grams of resistant starch per day.[14]

    What foods are highest in resistant starch?

    Here’s a table to help you figure that out…


    Resistant Starch

    Glycemic Index

    g/100 g

    Grain and cereal products




     Bread (white)



     Bread (wholemeal)






     Rice (brown)



     Rice (white)



     Spaghetti (wholemeal)



     Spaghetti (white)



    Breakfast cereals

     All-Bran (Kellogg's)









     Porridge oats



     Shredded wheat







     Broad beans



     Potatoes (white)



     Potatoes (sweet)










     Beans (baked)



     Beans (kidney)



     Peas (chick)






    Table 2: Comparison of resistant starch content and glycemic index for commonly consumed starchy foods[3]

    Now, a word of caution regarding intake of resistant starch. Research notes that resistant starch seems to be well tolerated up to an intake of around 40-45 grams per day. Should you consume more than that, you might be in store for some GI distress, including diarrhea and bloating. This is due to the fact that high amounts of resistant starch can more or less “overwhelm” the fermenting capacity of our gut bacteria.

    Also, if you’re coming from a diet that’s typically low in fiber and resistant starch, increase your intake of these type of foods slowly. Going from 0 to 100 with fiber is begging for a lot of gas, bloating, cramping, and trips to the bathroom.


    As demonized as carbohydrates are these days, it appears that resistant starch may be the one carb that all of us can get behind. They can aid blood sugar regulation and insulin sensitivity, improve gut health, help keep us full, and may even reduce our risk of various cancers.

    If you're struggling with weight loss, high blood sugars, or digestive problems, resistant starch provides an excellent option to get things moving in the right direction. Just remember to start slowly, or things are going to be freely flowing from you!


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