Resistant Starch 101: A Complete Beginner’s Guide
By: Dave Asprey
- Resistant starch is a type of starch that’s “resistant” to digestion — your body can’t break it down. Once resistant starch arrives in the colon intact, good bacteria feeds on it, producing beneficial short-chain fatty acids.
- Resistant starch carries many benefits: it strengthens the gut, burns fat, and protects against colon cancer, diabetes, and heart disease.
- The best sources of resistant starch are green banana and plantain flours, cooked and cooled white rice, and raw potato starch.
- Experiment with resistant starch and see how you feel — not everyone can tolerate it.
Starch isn’t a word you typically associate with the Bulletproof Diet. Sure, sweet potatoes, white rice, and carrots are fine to eat once a week or so (in fact, I encourage it). But healthy fats and vegetables, plus a bit of protein, are what you really want to focus on. However, there’s one type of starch that can radically transform your gut biome for the better — it’s called resistant starch. Read on to find out what it is, how to consume it, and all the ways it can help you perform at your best.
What is resistant starch?
Resistant starch is a type of starch that’s “resistant” to digestion — your body can’t break it down. Usually, enzymes in your small intestine digest starches and turn them into sugar. Resistant starch, however, moves through the stomach and small intestine undigested, and arrives in the colon intact.
Here’s where the fun stuff happens — resistant starch acts more like a prebiotic than a typical starch. A prebiotic is what your good gut bacteria (probiotics) eat. So once the resistant starch arrives in the colon, your good bacteria feeds on the starch, producing something called butyrate (butyric acid). Butyrate is a short-chain fatty acid that strengthens your brain and your gut.  Grass-fed butter is high in butyrate — one reason why it’s such an important element in the Bulletproof Diet.
The types of resistant starch
There are four types of resistant starch (take note that not all of these are Bulletproof-approved):
RS1: This type of resistant starch is embedded in the coating of seeds, nuts, grains, and legumes.
RS2: Type 2 is the resistant granules in green bananas and raw potatoes.
RS3: This type of starch transforms into resistant starch when cooked and then cooled, like white potatoes and white rice.
RS4: Here you have the man-made resistant starch — what you might see on a food label of a manufactured, processed food like bread or cake. The label might say polydextrin or modified starch. Man-made isn’t always a bad thing — a soluble fiber called resistant dextrin is in Bulletproof Instamix. One study found that resistant dextrin improved insulin resistance in women with type 2 diabetes.
The benefits of resistant starch
Along with strengthening the gut by feeding all that good bacteria, resistant starch has many other benefits, including:
Protects against colon cancer: Resistant starch could kill precancerous cells in the gut and shrink cancerous lesions in the bowel. A 2013 study found that mice fed resistant starch showed a decrease in the number and size of lesions tied to colon cancer. They also showed an increase in an anti-inflammatory protein called IL-10.
Reduces insulin resistance: Since resistant starch isn’t digested, your insulin doesn’t rise like other starches and cause blood sugar problems. A 2012 study found that obese men who were given 15 – 30 grams of resistant starch a day for four weeks showed increased insulin sensitivity compared to a control group who took zero resistant starch. Insulin sensitivity (aka low insulin resistance) is a good thing. If you have high insulin resistance, you’re at risk of serious conditions like type 2 diabetes, metabolic syndrome, heart disease, and obesity.
Burns fat and curbs hunger: Resistant starch could help you control your weight. One study found that women who ate pancakes made with a resistant starch plus protein burned more fat after the meal than women who ate pancakes without resistant starch. Another study found that adding resistant starch to meals could make you feel fuller quicker, causing you to eat fewer calories.
Improves sleep: Resistant starch can also help you sleep better. A 2017 study found that rats fed prebiotics had better non-REM sleep (the restorative phase) than rats who weren’t given prebiotics.
How to introduce it into your diet
Start with one tablespoon of raw potato starch a day and slowly ramp up the dose, depending on how it makes you feel. And don’t be afraid of the extra carbs — resistant starch is keto-friendly since it bypasses digestion, and isn’t broken down like a typical carbohydrate.
Some people respond well when they introduce resistant starch into their diet, while for others, it just doesn’t work. It can take 6 weeks or more for your body to get used to it, so keep that in mind when experimenting.
If you’re still experiencing gas and bloating after a few weeks, it might be worth getting your gut checked out. If you’re unable to handle resistant starch, you might have imbalanced gut bacteria. This may be the case if you’ve taken antibiotics or eaten industrially-produced meat in the past year. You can get a gastrointestinal pathogen panel or have the genetic sequencing of your gut bacteria looked at. I’ve done both, and it’s a worthwhile biohack if you have the time. You’ll likely need to take specific probiotics to fix the problem.
When I did potato starch, I had issues from the potato lectins (read here about the dangers of this protein). I developed a rash and my joints hurt. I quit doing the potato starch a couple of weeks after. But give it a try — every person’s body is different and you might have zero issues with it.
The best sources of resistant starch
Some resistant starch foods — like white potatoes and legumes — aren’t Bulletproof-friendly. Here’s a list of ones you can try. And remember: the key is to experiment and track how you feel after eating resistant starch. Some people do just fine with it, while others are bloated and gassy for days.
Raw potato starch: Bob’s Red Mill Potato Starch is a good brand. Don’t cook it, and rather dissolve in cold or lukewarm water or a smoothie.
Green bananas and raw plantains (including green banana and plantain flours): When choosing bananas, go for the greenest ones — they might not taste as good but they’re the highest in resistant starch. Try this recipe for White Chocolate and Raspberry Keto Cake that uses green banana flour.
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