Resistant starch might explain the great health and low cancer rates in traditional cultures where high-carbohydrate foods are the staple. However, many of us biohackers go overboard on resistant starch and experience some unpleasant side effects.
This post includes the definition and types of resistant starch, ways to increase resistant starch in your diet, and also our personal experience with it.
What Is Resistant Starch?
Resistant starches are the starches that are resistant to digestion in the small intestine. Therefore, they survive digestion and do not get absorbed in the small intestine, but then get fermented by the gut bacteria in the large intestine [1, 2, 3].
Resistant starches also don’t increase blood sugar like typical non-resistant (digestible) starches do.
This undigested starch then goes to the large intestine and feeds good bacteria that in turn produce butyrate and vitamin K2, both of which have many positive effects on the body. In addition, the friendly bacteria multiply, which benefits gut and immune health.
Sources of Resistant Starch
However, some whole food sources of resistant starch have a combination of resistant and non-resistant starches, so the actual glycemic indices of these foods vary.
There are five different types of resistant starch, as categorized by their sources:
- RS Type 1 – Starch that is physically inaccessible to digestion because it is trapped in the fibrous cell walls of plants. RS Type 1 is found in coarsely-ground or whole cereal grains, seeds, and legumes (beans, nuts, peas, and lentils)
- RS Type 2 – Non-gelatinized starch has high amylose content. Amylose is a type of starch with a linear structure, which makes it more easily packed (crystallized into a structure that prevents digestion. RS Type 2 is indigestible when it’s raw. RS Type 2 is found in starchy fruits (green bananas), raw vegetables (potatoes), and high-amylose starches (maize starch)
- RS Type 3 – Retrograded starch that forms after type 1 or 2 are cooked and then cooled. Type 3 can be reheated at low temperatures to keep the starch from becoming digestible. RS Type 3 is found in bread, pasta, rice, and potatoes. Cooked potatoes and banana starches lose their resistance, but cooked high-amylose maize starch partially retains resistance to digestion 
- RS Type 4 – Starch that has been chemically modified (esterified starches) to resist digestion. RS Type 4 is chemically modified starch found in processed foods like bread and crackers. Examples are hi-maize starch, cross-linked starches, starch esters and ethers, and cyclodextrins [7, 6, 5]
- RS Type 5 – Starch with amylopectin (a type of starch with non-linear, branching structure) that has been heated with oil and form a helical structure that makes it resistant to digestion 
All types of RS are beneficial for health, but they have different effects on your body .
Cooking Methods That Increase Type 3 Resistant Starch Content
1) Cooking and Cooling Carbs
When foods with resistant starch are cooked, the starch loses resistance. There are cooking methods that maintain resistant starch content. When starch that is high in amylose is heated in water, the starch granules absorb water and swell up. After the cooked starch is cooled, the starch (amylose) molecules rearrange structures (crystalize) and become less digestible. This process is called retrogradation.
Cooked and cooled starchy foods with resistant starch may be reheated at low temperatures (below 175 °F) to maintain resistant starch content .
2) Baked and Chilled Potatoes vs Boiled Potatoes
Baking does not degrade the starch as much as boiling does. Chilled potatoes (40 °F ) have more resistant starch than hot (150 °F) or reheated potatoes (40 °F for 6 days and reheated at 150 °F). The chilled potatoes have retrograded starch, which is less digestible than cooked starch .
3) Cooked and Cooled Rice
You can learn more about Joe’s resistant starch diet for weight loss in this post.
Supplemental Sources of Resistant Starch
Besides consuming starchy fruits, vegetables, and foods listed above, an easy way to include natural resistant starch in your diet is to add resistant starch to your foods.
1) Raw Potato Starch
Raw potato starch has by far the highest content of resistant starch and the lowest glycemic index. Corn has the next highest content of resistant starch, followed by tapioca, wheat, and rice .
Hi-maize is a high-amylose resistant starch that has been treated with heat and moisture to significantly increases its resistant starch content .
If you’re sensitive to plant-based starches, Hi-maize is a good hypoallergenic alternative. It does not come from a nightshade plant and the processing destroys most plant-based immune stimulants. (However, if you have an IgE true allergy against corn, I would suggest you avoid it.)
Hi-maize has a uniquely high amount of resistant starch and dietary fiber. Hi-maize starch is 50 percent resistant starch. One serving (11 grams) contains 7 grams of dietary fiber (source: Ingredion). Unlike other natural sources of resistant starch, Hi-maize has a high gelatinization temperature that ensures its ability to survive and remain resistant through most normal food processing conditions [16, 17].
Hi-maize is used in a variety of processed foods, including low-fat snacks, high-fiber bread, noodles, pasta, breakfast cereal, and gluten-free products .
Our Personal Experiences with Resistant Starch
We use a lot of Hi-Maize at SelfHacked HQ, which is why we include a lot of recipes that contain Hi-Maize in the Lectin Avoidance Diet Cookbook. We also often recommend Hi-Maize to our clients, especially ones who have digestive problems, dysbiosis, or are figuring out which whole-food sources of carbohydrates work for them.
Joe’s experience: I don’t tolerate nightshades, so I can’t use potato starches. I personally am sensitive to many plant-based substances, so I usually don’t do well with a lot of vegetables or tubers. I tolerate Hi-Maize well because it has already stripped off most substances that provoke immune responses. I find that if I don’t consistently supplement with Hi-Maize and probiotics, then I’m more likely to get food poisoning (even from foods that don’t seem to bother other people).
If I go overboard with the Hi-Maize, it causes nausea.
Nattha’s experience: I tolerate white potatoes and white rice, so cooked and cooled white rice and white potatoes are staples in my diet. I usually pressure cook them to reduce the harmful lectins anyway. I find that even though these foods contain resistant starch, they still raise my blood sugar (see graphs below), so I typically limit these for supper. The calming effects of meals with rice or potatoes help me sleep better and deeper at night.
I also supplement with Hi-Maize or potato starches in my bone broth for breakfast and find that it does not have the same calming effects as the rice and potatoes. The morning dose of resistant starch seems to help me feel full longer and improves my cognitive function in the morning.
I have also personally tried the Potato Hacks for three days, so here I will share my results.
The Potato Hack Diet Results
The Potato Hack Diet is based on the assumption that:
- Cooked and cooled potatoes contain resistant starch, so consuming only cooked and cooled potatoes helps with rapid weight loss.
- The changes in the gut microbiome from high amounts of resistant starch should help with weight loss.
- The low palatability of the diet should reduce appetite.
I had always felt that the cooked and cooled potatoes were more filling than the freshly cooked potatoes. In addition, if I cooled down the potatoes, I wouldn’t get the carb crash from eating them.
So, I designed an experiment to answer these questions. It’s a hypothesis-driven and somewhat controlled experiment, but it’s not a blinded study.
- Does the cooking and cooling actually decrease the glycemic impact of the potatoes?
- Does the Potato Hack actually work for fat loss?
To establish a baseline, first I used my glucometer to measure my post-meal blood sugar until the blood sugar levels returned to pre-meal (around 90 mg/dL) levels.
As expected, my blood sugar from my typical low carb meals didn’t rise much. It went up to around 100 mg/dL and came back down after a few hours. If I added rice to the meal, this did increase the blood sugar, but it wasn’t excessively high.
Next, I got myself about 15 lbs of white potatoes, cooked them in a big batch, and cooled them down in the fridge. The only seasoning allowed would be sea salt and pepper.
In one meal, I ate the potatoes that were cooked and cooled. In another meal, I ate the potatoes that were cooked but not cooled. Then, I measured my blood sugar in the hours after eating it until the blood sugar would return to baseline levels (around 90 mg/dL).
It turns out my blood sugar did go up really high whether the potatoes were cooled down or not. However, while all the potatoes gave me very high post-meal blood sugar, the cooked and not cooled potatoes gave me more of a reactive hypoglycemic response that the cooked and cooled potatoes did not. That meant that I was jittery and my heart was racing while my blood sugar dipped to around 70 mg/dL. I suspect that this was because the cooked and cooled potatoes mitigated some of the insulin responses.
In terms of weight loss, I tracked my body weight and body fat (using a Tanita scale) before the Potato Hacks and each day during it. I found that both the body weight and body fat went down.
My body weight went down from 161 lbs to 159.6 lbs. My body fat went down from 31.6% to 30.5%. At 1.4 lbs and 1.1% body fat over the span of 3 days, this is pretty fast fat loss for someone who is not obese, since I almost never lose more than 1 lb per week.
Note that the Tanita scale might not be the most accurate way to measure body fat, but comparatively, if I measured the same way at the same time every day, this was reliable.
Other experiences: I was significantly more fatigued and overall didn’t feel great during these three days. Inflammation levels were about the same otherwise. I usually don’t have any problems with digestive function and elimination, and these remained the same.
Conclusion: I would recommend this hack to someone who wants to lose fat or break through a fat loss plateau, although not if you are diabetic or severely insulin resistant.
Types of Starch
There are two types of starch based on their branching chemical structures, i.e. amylose and amylopectin.
Digestible vs. Resistant Starch
Starches are also categorized based on digestibility and glycemic index (the speed at which the starch increases blood sugar):
- Rapidly digestible starch – causes a sudden increase in blood glucose level after ingestion. Rapidly digestible starch is found in white bread and sugary breakfast cereals
- Slowly digestible starch – digests completely in the small intestine at a lower rate than rapidly digestible starch. Pasta, brown rice, barley, oatmeal, and whole wheat bread contain slowly digestible starch
- Resistant starch – does not absorb in the small intestine and is fermented in the large intestine
Buy Resistant Starch
Also, check out the Lectin Avoidance Diet Cookbook if you have many food sensitivities but would like to take advantage of the health benefits of resistant starch.