Cooking, Cooling, and Reheating Starches For Even More Digestive Resistance

One of the more common questions we’ve had since the very beginning of the Resistant Starch Explosion is: if cooling your cooked starches (e.g., potatoes, rice, beans, pasta) increases the resistant starch (retrograded RS3), will reheating it destroy it?

It was Tim Steele who came up with the info that not only does it not destroy the RS3, successive cooling and reheating actually increases it—though the the first cycle is by far the biggest bang.

Well, so now we have some testing on real people, using pasta: Is reheated pasta less fattening?

The volunteers were randomised to eating either hot, cold or reheated pasta on different days.

On one day they got to eat the pasta, freshly cooked, nice and hot with a plain but delicious sauce of tomatoes and garlic.

On another day they had to eat it cold, with the same sauce, but after it had been chilled overnight.

And on a third day they got to eat the pasta with sauce after it had been chilled and then reheated.

So what did happen?

Well we were fairly confident the cold pasta would be more resistant than the stuff that had been freshly cooked and we were right.

Just as expected, eating cold pasta led to a smaller spike in blood glucose and insulin than eating freshly boiled pasta had.

But then we found something that we really didn’t expect – cooking, cooling and then reheating the pasta had an even more dramatic effect. Or, to be precise, an even smaller effect on blood glucose.

In fact, it reduced the rise in blood glucose by 50%.

So there you have it. Short & simple, too.

It makes me wonder if this is why I didn’t get fat eating all that pasta at the mom & pop Sicilian place down the street from my flat when I lived in France. I’d walk down 2-3 times per week and if it wasn’t a wood fired pizza, it was a bowl of pasta. But I recall one evening asking their son, Salvatore (who’s limonadier he gave me when I left is still used to open wine around here, 22 years later), how they do their pasta so quickly, in single batches.

They precook it and put it in the fridge. Then they reheat in salty, boiling water, portion by portion. Go figure.

Update: OK, found the actual program website, as well as the short video segment.

And here’s a chart I clipped.

Screen Shot 2014 10 16 at 11 38 58 AM

Update 2: This appears to work for freezing and toasting bread, too.

The impact of freezing and toasting on the glycaemic response of white bread.

CONCLUSIONS: All three procedures investigated, freezing and defrosting, toasting from fresh, and toasting following freezing and defrosting, favourably altered the glucose response of the breads. This is the first study known to the authors to show reductions in glycaemic response as a result of changes in storage conditions and the preparation of white bread before consumption. In addition, the study highlights a need to define and maintain storage conditions of white bread if used as a reference food in the determination of the glycaemic index of foods.

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  1. Starch+lvr on October 16, 2014 at 09:27

    I have heard not to reheat above 130 degrees, or the RS3 would partially revert.

    Obviously, not true, since the temp needed for
    boiling cold pasta is 212 degrees.

    Nice to know.

    • newbie on October 16, 2014 at 12:22

      In fact, all previous FTA posts said not above 104 deg. – Richard or Tim, would you weigh in with your research/thoughts? When I reheat fried rice, I’m pretty sure it gets hotter than 104!

    • Richard Nikoley on October 16, 2014 at 12:41

      You’re confusing things. It’s 140 F, and that’s initial heating of raw potato starch RS2, not reheating of previously cooked starchy foods RS3, in which case, we don’t really know an upper limit for reheating and potentially destroying RS3. The structures are wildly different.

    • newbie on October 16, 2014 at 15:21

      THANKS :)

  2. Starch+lvr on October 16, 2014 at 09:37

    The other thing of curiosity, does baking potatoes and cooling them to room temperature in a 24 hour period, increase RS3?

    My guess would be no. But to me, I can eat those room temperature potatoes like they were candy and to know they had increased RS3 would be a stroke of luck for my eating pattern.

    • Richard Nikoley on October 16, 2014 at 10:40

      That’s easy. Bake them, put in fridge overnight, take them out to come up to room temp. They last for days on the countertop.

    • Maggie on August 16, 2015 at 08:01

      Unfortunately, it’s not safe to store potatoes at room temperature. You might be lucky, but botulism toxins have been found in potatoes not refrigerated.

    • Chris Guth on September 14, 2018 at 08:21

      I would like to know if heating and cooling rice or potato cuts the insulin response or cuts the amount of glucose released. would it be even better to repeate the heat and cool process over and over to make more RS and have even more benefits???

  3. Geoffrey on October 16, 2014 at 10:41

    that’s awesome. I just had cooked, cooled, and reheated fried rice, which I think falls under the same category. And because I had a hamburger for breakfast (between two organic corn soft tortillas), I didn’t eat any meat for lunch and my stomach is happy. Too much meat is too much for my gut, if only I had listened more and taken it seriously the past 3 years.

    And yes, I think cooked, then cooled potatoes have increased RS3.

    • gabkad on October 16, 2014 at 19:28

      Geoffrey, eat meat only once per 24 hours if that’s what you eat. It takes a long time to break down beef. Even longer if you drink some wine with it. All that gastric acid has to be produced for a long time. It can cause problems.

  4. eddings on October 16, 2014 at 11:10

    this is what’s always bugged me about the line of reasoning that goes “east asians eat a lot of rice, and they’re pretty skinny, thus carbs don’t make you fat.” yeah, well, how much of that rice has been cooked, then cooled, then either re-heated or eaten cold?

    re the italian restaurant in france: “They precook it and put it in the fridge.” ha, yeah, at the mom-n-pop italian place i worked at in college, the owner and the cook would come in early on thursday or friday and cook just tons and tons of lasagna and other dishes, then cut, re-heat, and serve those for the next week.

  5. Jack on October 16, 2014 at 12:27

    What about other grains, like corn and wheat? Is there a similar effect?

    • Richard Nikoley on October 16, 2014 at 13:32

      Well, most pasta is wheat and I’m sure that’s what they were using here. Corn, don’t know.

  6. Romeo+Stevens on October 16, 2014 at 13:02

    This is great news for us, we were concerned about our beta-testers wanting to reheat mealsquares, but this indicates it is probably actually good for them. Awesome stuff.

  7. rick on October 16, 2014 at 14:28

    Richard, You’re awesome, I was sitting at my desk eating Fried Rice (Uncle Ben’s,cooked,frozen,fried,refrigerated,nuked for lunch) and wondering if this(the nuking) was OK for it’s RS content, when I clicked over to your site to find this post. And you think there is no doG!

  8. Rob2 on October 16, 2014 at 14:55

    I wonder if this heating, cooling, heating works with, dare I say it, Bread? It is initially baked, cooled and then often toasted which is the re-heat. Both pasta and bread have wheat as an ingredient, so it seems feasible.

    • Richard Nikoley on October 16, 2014 at 15:41

      I was thinking the same thing, but also, bread reconstitutes really well from frozen.

    • FrenchFry on October 17, 2014 at 03:19

      Doesn’t it depend on how fine the flour used had been milled ? Super finely milled flour would have its starch granules destroyed. I wonder how much could turn to RS3 …

    • urubu on October 19, 2014 at 14:03

      Possibly relevant:

      The impact of freezing and toasting on the glycaemic response of white bread.
      PMID: 17426743:

      All three procedures investigated, freezing and defrosting, toasting from fresh, and toasting following freezing and defrosting, favourably altered the glucose response of the breads. (…)”

    • Richard Nikoley on October 20, 2014 at 07:48

      Great find, urubu. Added it to the post.

  9. gabkad on October 16, 2014 at 19:31

    Okay good. I’ll cook up a batch of gluten free pasta, mix in some good olive oil and put it in the fridge. Warm up when needed. Sounds like a plan.

    • Chris G on February 5, 2015 at 18:19

      Maybe don’t freeze the gluten free pasta. Testing here says just let it cool in the fridge… or be prepared for odd, crumbly texture.

  10. james london on October 17, 2014 at 01:33

    Well I wasn’t ever expecting to see Guildford high street on Free the Animal… that’s the town shown in the clip, home to the University of Surrey and near where I grew up.

    Was nuking mentioned anywhere? I’d also like to know if it makes any difference compared to normal re-heating.

    I’ve eaten re-heated food 2-3 nights a week for most of my adult life (I’m 49), nearly always with rice/pasta/potatoes. While I’ve been slowly getting rid of various problems caused by mercury toxicity from 3 years ago, I’ve recently been coming to the view that my gut may not have been a big part of the problem (I have had no GI symptoms) and this rather seems to back that up, and my diet was never that terrible anyway.

  11. Alex on October 17, 2014 at 06:38

    Hmm, so I just bought the 3 probiotics and now I’m wondering whether or not I should bring my bag of potato starch with me on my carry on bag for these 4 business trips I have coming up over the next month.

    You think I’m going to be detained every time? Damn TSA lol. I’m on a budget, can’t go buying a whole bag of potato starch in every city and throwing it away when I don’t use all of it.

    • Charles on October 17, 2014 at 07:44

      I’ve been carrying my potato (and other white) starches around with me for a year or so. I’ve gone through the TSA lines dozens of times and never had a problem. Same thing over the border.

    • sdiguana on October 17, 2014 at 10:38

      I imagine if you keep it in the original packaging with a rubber band or the black paper clamps (not sure the right name for them) to keep it sealed, I cant see them getting wound up. An unlabeled jar of white powder could be less diffusing to Those Smart Agents.

    • Charles on October 17, 2014 at 10:51

      I have just kept mine in a big ziploc or a small container. I’ve never even had it questioned, and as I said I’ve gone through dozens of times. A lot of people go through security with various powders and potions. I really wouldn’t worry about it.

  12. Simas on October 17, 2014 at 14:19

    I think there’s a major flaw in this test. They did the reheated pasta experiment after the day that they did cold pasta. RS from cold pasta may have contributed to better glucose control on third day. Just like a bean effect.

    • Richard Nikoley on October 17, 2014 at 18:26

      You didn’t catch it was randomized? That’s what I saw somewhere, anyway.

      The 2nd meal effect is not so profound and doesn’t last that long. OTOH, why not make absolutely sure?

      OTOOH, it does confirm that RS3 structures get tighter with reheating.

    • FrenchFry on October 18, 2014 at 01:11

      I don’t think so. I think there were many days between the different pasta meals, something like one week in between.

    • Bruce Brooks Jr on March 1, 2019 at 07:22

      I love pasta but am type2. I tried the test took the cold pasta from the fridge that I cooked the day before heated it in the microwave tested before eating and tested 2hrs after and my index showed a drop in mgl!

  13. Bay+Area+Sparky on October 17, 2014 at 15:50

    Well these findings are very exciting especially coming just before the weekend.

    Tonight I’m gonna reheat yesterday’s pizza for dinner and wash it down with a few heated and cooled hefeweizen!

    • Richard Nikoley on October 17, 2014 at 18:45

      Well there’s a problem I hadn’t considered. I prefer my leftover pizza cold.

      Actually, my real preference is room temperature, with some bites taken out of it…and empty and partially empty beer bottles strewn about, the carpet smelling of nasty bong water and one or two girls still crashed out on sofas and that awful 60’s orange vinyl bean bag, all with faint hints of 11 am Saturday morning peeking through the purple and violet plaid drapes.

  14. Charlie on October 18, 2014 at 12:01

    I’m surprised the cold pasta didn’t do better than it did…

  15. Charlie on October 18, 2014 at 12:03

    My question would be: at what minimum temp does the reheated starch reach it’s max benefit? Is room temp good enough?

  16. Weekly sparks | purelytwins on October 19, 2014 at 05:53

    […] Reheating starches for more digestive resistance […]

  17. Bill Campbell on October 19, 2014 at 11:24

    Hi, Richard…Just ran into this piece of info re the difference between RS2 from potato starch and RS3 from cooked/cooled/reheated foods, and an apparent link between the potato starch and the formation of colorectal cancer:

    I know you’ve been a heavy proponent of the potato starch as a good alternative to getting the RS from foods, so I was wondering what your (and Tim Steele’s) take on it might be. Thanks. This is all so damned confusing!

    • Richard Nikoley on October 20, 2014 at 07:33

      That thing keeps cropping it’s head.

      I think Sisson dealt with it here:

    • Bill Campbell on October 20, 2014 at 08:01

      Thanks…I had read Sisson’s treatment as well, but I noted that the research cited above wasn’t an indictment on all RS, but only potato starch in particular. Of course, they don’t speculate (as far as I can tell) on the causes, unlike Sisson who specifies butyric acid production. Are you aware of anything that counters that potato starch indictment? Obviously, my wife and I are concerned…we’ve been doing upwards of 4 Tbs of potato starch daily.

    • Richard Nikoley on October 20, 2014 at 08:34

      “we’ve been doing upwards of 4 Tbs of potato starch daily.”

      Well, dose makes the poison, even in water, right?

      There’s lots of variables, including time. So say it takes 20 years for colon cancer to develop for taking 4 TBS daily of raw isolated potato starch? Any chance other risk factors you’re unaware of kill you first.

      I think PS is a great tool to pound initially for a while, but really, only to convince you in no uncertain terms that the gut biome stuff is real and important. Then, naturally, you’ll want to gravitate to the favors foods with various fibers to feed it well. So by then, maybe you’re only doing a few tsp of PS weekly just as a hedge, and now it takes 60 years to kill you.

  18. Dr.+Curmudgeon+Gee on October 19, 2014 at 18:28

    ok. i’m no expert in RS

    but there’re many reasons that pasta did not make you fat

    1) you were younger

    2) wheat in Europe was less genetically “altered” than US (probably still is according to my Bulgarian colleague; they still grow & eat einkorn wheat)

    3) the lifestyle may be less stressful, more pleasant, perhaps?

    4) the food in France is more wholesome in general

  19. John+Es on October 19, 2014 at 18:58

    I find so many of the conclusions, here, questionable. Even laughable (sorry).

    Haven’t we learned that there are no simple rules when it comes to starches, particularly when it comes to formation of RS3? Anecdotes exist making all sorts of claims, much of it based on blood glucose monitoring. C’mon man, those are not well controlled measurements, they can’t be. Food A forms more RS3 when gently cooked and cooled, and Food B forms more when harshly cooked and cooled. Be careful not to overdo it when reheating. No, wait, reheat with reckless abandon!

    Someday we’ll have better data, and I applaud those conducting the experiments. I am nowhere near ready to believe some universal rule. I think there are probably different rules for different foods.

    My suspicion is that amylose starches have more promise, and might be more worthy of pursuit for the holy grail of real food RS3. Look at the rices that form more RS3. Notice the amylose vs. amylopectin. This too, is certainly an oversimplification.

    Maybe if animal studies translate well to humans, some good data can get generated in a short amount of time. I guess that would be bad news for RS2, if the rat turns out to be a good animal for these studies.

  20. Naman on April 24, 2015 at 16:28

    So Richard, does it matter if I boil or
    bake my potatoes?
    Next, what about beans? Can boiling them and then cooling them and then reheating them work too?

    Will RS3 be lost if I slice my potatoes into finger shapes,
    and then boil them and then cool them? (Sorry if I sound stupid here).
    Will it be perfect if I cook beans and potatoes and cool them and then reheat them and cool them and then reheat?
    Or just cooking then cooling and reheating only one works?
    Will this work together with the method of adding coconut oil into rice being boiled or after they’re boiled (I forgot), to cut its calories?
    Thanks and this was a very informative article! I’m on a keto diet and been starting to introduce now carbs slowly back into my diet.

    • Richard Nikoley on April 24, 2015 at 18:32


      Do it all. Do everything like that. Eat it all according to hunger.

      There’s no “best” way.

    • Naman on April 25, 2015 at 15:55

      Haha thanks for the prompt reply Richard, I owe you one!
      Just want to really know one thing, does this method (of lowering its spike effect)of cooking requires baking or boiling finger cut chips?
      I tried to experiment drinking 4tbsp of potato starch diluted in water and a tbsp of apple cider vinegar before I sat down to eat 2 medium pizzas (cheat day). And I don’t feel like my sugar system is crashing.. like it’s suppo

    • Naman on April 25, 2015 at 15:59

      Supposed to!*
      Thanks big time for this discovery.
      My Paki family has potatoes and rice as the staple.
      They don’t like my keto diet, and still they want to eat high carbs and low fat and moderate protein.
      I’m sure introducing Potato starch to their diets will help…
      Thank you man. I can’t thank you enough! :)

    • Zaak on February 27, 2017 at 20:30

      Naman: It does matter!
      More specifically, regardless of potato variety, the baked potatoes had significantly higher resistant starch at 3.6 grams of starch per 100 grams of food (3.6/100g on average) than boiled potatoes (2.4/100g). Also on average, chilled potatoes (whether originally baked or boiled) contained the most resistant starch (4.3/100g ) followed by chilled-and-reheated potatoes (3.5/100g) and potatoes served hot (3.1/100g).

  21. Mexigirl on August 5, 2015 at 16:26

    What about adding PS to, i.e., mashed potatoes, throw in an egg & make potato patties with the mix — then refrigerate, & reheat in oil. Any ideas on whether the PS would become RS3? IF so, it would increase the RS of the potato patties considerably — & not be “isolated”.

    • newbie on August 5, 2015 at 18:09

      The PS would stay as RS2, some of the RS2 of the previously cooked potato would reform as RS3, although the majority is turned into digestable starch by the cooking process – in other words, neither RS2 nor RS3. The PS does not turn into RS3 by being put into the fridge.

  22. Charlie on August 25, 2015 at 20:07

    How long does the pasta have to be chilled? After cooking it, can I just run cold water over it to cool it down and then reheat it back up with hot tap water? How cold and how long does it have be cold to become resistant starch?

    • FrenchFry on August 26, 2015 at 00:28

      Overnight in the fridge.

    • Charlie on August 26, 2015 at 05:03

      FrenchFry, I’m not insulting you but I want to ask you, how do you know this, where did you get the information that the pasta has to be chilled over night?

    • FrenchFry on August 26, 2015 at 05:54

      Hey Charlie,

      No worry, you are not insulting me just by asking something like that!

      I remember reading this from Tim Steele (aka tatertot) who had researched the topic quite in depth. It was a long time ago but I vaguely remember a figure stating tha the optimal cooling should be around 4-5 deg for at least 8 hours. I did not save any link or reference so I hope he can eventually chime in.

      In any case, I don’t see any issue with eating pasta that you have just cooked! But make sure you cook enough so you have plenty of leftovers you can cool down overnight :) That’s how I do potatoes: I cook rather huge batches that last me a full week at a time. When I run out, I repeat the process. I won’t ignore freshly cooked potatoes, I would find myself silly doing that :D

    • Charlie on August 26, 2015 at 16:05


  23. Zed on September 6, 2015 at 00:02

    i wonder if microwaving for reheating is an issue

  24. Angie on September 17, 2015 at 05:35

    Do you know if oatmeal becomes a resistant starch after being cooked and cooled? I saw an RS list that included uncooked oatmeal and cooked oatmeal, but not cooked and cooled.

  25. Primal foods for endurance workouts.... | Mark's Daily Apple Health and Fitness Forum page on October 22, 2015 at 04:19

    […] all kind and of course cooked, cooled then reheated potatoes which will contain resistant starch: Cooking, Cooling, and Reheating Starches For Even More Digestive Resistance | Free The Animal Take a walk on the wild side. Reply With […]

  26. […] Link: Cooking, Cooling, and Reheating Starches For Even More Digestive Resistance […]

  27. Susan Eapen on November 23, 2015 at 20:34

    I am Indian, living near the Southernmost tip of the subcontinent in Thiruvananthapuram. The staple of our area used to be rice. We use a red coloured rice which is parboiled. That is, before de-husking the rice, the grain is boiled, left overnight in the water, strained, dried in the sun, milled to remove husk and we get our rice. The breakfast was often leftover cooked rice from previous day soaked in water overnight, eaten with curds and chutney. The rice was slightly fermented and the curd is fermented milk. This has now been replaced by wheat, breads, cereals, idli-dosa etc. I believe that this rice could also have been full of resistant starch, probiotics etc.

  28. Kylie James on January 14, 2017 at 22:57

    Has anyone tried or do you think that when cooking the potatos you could use chicken stock instead of water?
    Would they still be RS?

  29. DIY Healthy Baked Potatoes, Pasta, Corn and more! – The wisdom of ZO on February 27, 2017 at 14:13

    […] Does reheating negate the RS created by cooling? NO! It enhances it further! […]

  30. Richard Nikoley on October 25, 2017 at 14:15

    Melbot posts:

    One thing confusing me about this whole thing. Since a loaf of white bread is flour that has already been cooked and cooled, why isn’t that already resistant? We’re always told to avoid white bread, but if that’s the case, it shouldn’t be a problem. OR is it actually, the second reheat/cool that matters. Anyone have any insight?

  31. carol on January 18, 2018 at 05:08

    does the cooling off and reheating pasta work the same for whole wheat pasta?

  32. Jami on January 29, 2018 at 19:40

    If the RS value increases with heating and cooling, then why am I reading that baking with banan flour destroys the RS value??? Is there ANY RS flour that can be baked that is NOT destroyed at 350 degrees????????

  33. Midge on July 5, 2019 at 16:41

    What about reheating with a microwave??

  34. Linda Camp on November 18, 2020 at 18:06

    Does this apply to instant mashed potatoes in a box? You know… like Idahoan instant potato flakes?

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