The truth about resistant starch.

Andrew Taylor - Spud Fit | June 4, 2019

Resistant starch has been in the spotlight lately and I’m constantly hearing from people who are focused on increasing their resistant starch intake to maximise weight loss.

First, the basics. Resistant starch is a specific type of starch that is present in all potatoes and other starchy foods in varying amounts. It is less digestible and so fewer calories can be absorbed, it also works a lot like fibre in that it aids digestion and helps feed good gut bacteria. Resistant starch content in foods can be increased by cooking and then cooling starchy food before eating it. Reheating is fine too, it won’t reduce the resistant starch content.
Now for the big questions that I get every day: 
  1. Is it worth the effort?
  2. Will I still lose weight if I don’t cool my potatoes before eating them?
Potatoes contain around 2-3 grams of resistant starch per 100 grams of total weight, depending on the variety. For argument’s sake, let’s use the upper measurement. Cooling after cooking increases the resistant starch content by around 10%, so 3 grams would become 3.3 grams. On my year of potatoes I was eating around 3000 grams of potatoes per day*, which works out to be around 90 grams of resistant starch. If they were all cooled before eating then I would’ve increased my resistant starch intake by a whopping 9 grams! (sarcasm intended)
Stay with me. Carbohydrates contain 4 calories per gram, meaning 9 grams of starch would yield 36 calories. We are only able to digest around half the calories in resistant starch, meaning that all the effort of cooking and cooling all my potatoes before eating has resulted in saving myself 18 calories for the day.
Potatoes (and rice, and beans) are a great source of resistant starch, however you eat them. The difference from cooling them is so tiny that the only good reason I can think of for cooling your food before eating it, is if you’re storing leftovers in the fridge for tomorrow. Food hygiene is important!
My advice to those of you who want to increase your intake of resistant starch by cooling food before eating it? Life is short, find something better to do with your time!

Spud up!

*please DO NOT use that as a guide for how much you should eat! Click HERE to see my rules.

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15 Replies to “The truth about resistant starch.”

  1. You are missing one important detail - raw potatoes are all resistant starch. That's about 80% resistant starch (not 2-3%). If they are dried down with harsh conditions, a lot of the resistant starch can be lost or destroyed, but it is possible to dry them down carefully and preserve 70% of the resistant starch (MSPrebiotic sells this). Bob's Red Mill potato starch is dried more harshly and does not specify or report the resistant starch content of their ingredient. When I have tested it, it is usually between 50-60% resistant starch. If you were to cook either of these, the resistant starch content would fall to about 3-5% Cooling them increases it modestly - to about 5-6%. See I agree with you completely that it is not worth eating cooked and cooled starchy foods to get the modest amount of resistant starch. But, I completely disagree with you about raw potato starch, which is an excellent supplement and a great way to add resistant starch into the diet without adding lots of high glycemic carbs. But, you can get the maximum benefits if you choose the highest quality supplement that guarantees the most resistant starch. Also, calorie reduction is the least of resistant starch's benefits. When resistant starch is consumed by the probiotic bacteria in the gut, they produce short-chain fatty acids (SCFAs) and other metabolites. One of the SCFAs, butyrate, actively feeds the colon cells (one of the few cells in the body that does not get its food from the blood). This process is called fermentation. If colon cells do not get butyrate, they shrink and get diseased, creating a leaky gut. If you feed them resistant starch in the presence of probiotic bacteria, they get fat and happy again, healing a leaky gut. Also, this fermentation changes the expression of >200 genes in the large intestine, which control insulin sensitivity, satiety, lipid oxidation, gut motility and many other aspects of metabolism. The calorie control is not even worth mentioning in the face of all of these fermentation-related benefits of resistant starch. See for more in-depth explanations of these benefits.

    1. Don't know of any data showing that people who are already eating a diet high in whole, starchy plant foods do any better with supplementation. I'd love to see the data if you have it.

  2. Hi, Andrew. I think I am somewhat confused. For over two years I have been reading that it is important to cool the potatoes after cooking them. I also saw the BBC program showing the difference between cooked and cooled pasta and eating the freshly cooked pasta. I am sure you have seen that program. I feel quite silly that I repeated to all my friends that it was important to cool the potatoes (and rice, bread, pasta) after cooking it to get that wonderful resistant starch. O well - I still love my potatoes, my comfort food. I have asthma and all the steroids flush potassium from my body in a big way (that's one of the reasons people on Prednisone puff up - retaining the salt), so I am so glad I have another reason to enjoy my wonderful potato meals.
    Somehow I still think that if I eat fresh pasta or potatoes, I feel sleepy and sluggish. If I eat leftovers, it does not happen to me. ?????

  3. Hi, could you advise please. If I cook with potato starch and then cool it, is it still resistant starch or is the absorbed carb higher? Thanks very much for your help.

  4. Yes. Use small potatoes in smoothies and get rs and thicker smoothies. BRM IS NOT resistant starch. Customer Service is ever waiting for folks to actually ask THEM instead of assuming. It is made using high heat; can't' be marketed as RS. Anthony's on the other hand is rs. Package says so. 50% per serving.
    Someone named Dr, Mark Hyman used to recommend Anthony's per a comment in a review on amazon, but now I discovered when asking them he recommends BRM. He is wrong.

    Anyway.... for now am using raw potatoes in smoothies. Was intrigued by supplementation. Tried BRM; got all stopped up. Gave up. Discovered Anthonys but haven't bought.

  5. With every cycle of heating a cooling, more of the starch in the potatoes becomes resistant starch. Therefore, if you preform multiple cycles, you could potentially create potatoes which are almost entirely resistant starch. This can be important if you are on a low carb diet and still want to eat potatoes or if you are having gut issues since the microbiome can digest resistant starch and create a thriving environment in the gut.

    1. So much more trouble than it's worth. The potatoes would be no good by the time you did it enough times to make any really meaningful difference.

  6. I don't know where you got your "increases by only 10%" information, but it is wrong. The NIH ran a study in 2015 that showed that cooling rice after cooking it doubled the amount of resistant starch while refrigerating it overnight nearly tripled it. Here is the link to the study:

    I would assume the resistant starch in potatoes would respond in the same fashion.

    Bon appetit!

    1. Best not to assume that white rice behaves the same as potatoes. Having sad that, even if it does double, it's still not much and in my opinion not worth the trouble

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