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Cook, Cool, Reheat: The Power of Resistant Starch

Doctor Alex

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Ever cooked a batch of rice, put it in the fridge overnight, then wondered if reheating it the next day cancels out any benefit at all? It turns out the temperature journey your food goes through after cooking can quietly reshape how much of it your body actually absorbs as sugar, and the science behind resistant starch explains exactly why.

This comes down to a process called starch retrogradation, one that changes rice, pasta, potatoes and even bread into something your gut treats more like fibre than carbohydrate.

In this video I'm answering the two questions that kept coming up after my last video on this topic. Does reheating your cooled rice or pasta undo the resistant starch you worked to create, and is there any truth to the worry that leftover rice is a food poisoning risk waiting to happen. I'll walk through what actually happens inside a pan of rice as it cools, why part of that structure survives the microwave while another part doesn't, and where the real danger with old rice actually comes from, because it isn't where the worry usually gets pointed.

I'll also get into the bread in the freezer trick so many of you asked about, plus a realistic look at how much any of this genuinely changes your blood sugar day to day. There's real science here, but plenty of nuance too, so I want to give you the full picture rather than a headline that oversimplifies it.

In this video you'll learn:
-What resistant starch actually is and why some starch resists digestion
-What happens inside rice, pasta and potatoes as they cool down
-Whether reheating your cooled carbohydrates undoes the benefit
-The real reason reheated rice can make you ill, and how to avoid it
-Why freezing your bread can gently lower its impact on blood sugar
-How much of a difference this genuinely makes to your glucose levels
-Who should be more careful with cooling and reheating starchy food
-Practical steps to cool, store and reheat rice and pasta safely

Whether you're trying to manage your blood sugar more closely, just curious about the science happening in your own kitchen, or a bit worried after hearing conflicting advice about food safety, this one should clear up exactly where the real risks and real benefits sit.

TIMESTAMPS
00:00 – Introduction
04:05 – What Resistant Starch Actually Is
09:42 – What Happens When You Let It Cool Down
14:36 – Whether Reheating Undoes It
17:00 – The Food Poisoning Question
21:53 – Bread in the Freezer
26:09 – How Much Difference This Actually Makes
30:43 – Where This Fits

REFERENCES
Effect of cooling of cooked white rice on resistant starch content and glycemic response
https://pubmed.ncbi.nlm.nih.gov/26693...

The impact of freezing and toasting on the glycaemic response of white bread
https://pubmed.ncbi.nlm.nih.gov/17426...

Production of Bacillus cereus emetic toxin (cereulide) in various foods
https://pubmed.ncbi.nlm.nih.gov/11883...

Influence of resistant starch resulting from the cooling of rice on postprandial glycemia in type 1 diabetes
https://pubmed.ncbi.nlm.nih.gov/35429...

A comparison of the effects of resistant starch types on glycemic response in individuals with type 2 diabetes or prediabetes: A systematic review and meta-analysis
https://pubmed.ncbi.nlm.nih.gov/37051...

Resistant starch: promise for improving human health
https://pubmed.ncbi.nlm.nih.gov/24228...

Disclaimer: This is not personal medical advice and does not override what your doctor says.

#dralex #doctoralex #resistantstarch #bloodsugar #guthealth #foodscience

20 Comments

@DrAlexWibberley Creator 2 weeks ago (edited) Pinned

Join the fast-growing community! www.dralexnewsletter.com

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@BeverlySizer 2 weeks ago (edited)

As an RN, I have never heard anyone explain resistant starch as well as you did in this video. You improved my understanding of it and how it works exactly in our bodies. I try to eat very few refined carbs and concentrate mainly on eating whole foods, veggies, etc. I wear a CGM even though I’m not diabetic to monitor my metabolic health. When I eat a serving of cold pasta salad on occasion, I see a much smaller glucose spike and the spike comes down quickly. That’s the beauty of a CGM. You’re able to see first hand that these different measures you talk about actually work. You are a great teacher and I so appreciate what you do to help us all be the healthiest we can be. Thank you!

@PS-n5f 2 weeks ago (edited)

I get it! It's rock, paper, scissors: the scissor enzymes show up, but some of the paper starch has turned to rock, and we all know scissors can't cut rock.

@davidchutchings 4 days ago

Wow
Thanks

@christinebravomom5711 2 weeks ago

I remember a gajillion years ago when some guy on the internet suggested this might be a thing. He had lived in Italy for a while and gone to a local bistro every day for a plate of pasta. He lost weight there, then came home, continued with his daily pasta, but cooked at home. He gained the weight back which got him wondering what was different.

He learned that restaurants routinely pre-cook pasta, then refrigerate and reheat it so they can get meals plated quickly for hungry customers. As I recall, he started messing around with tracking his blood sugar after eating fresh cooked pasta vs. cooked-cooled-reheated pasta and saw a difference. Then, he made a video and kind of threw the idea out into the ether.

I had just learned about the benefits of resistant starch for the gut biome, so I was mainly interested in that aspect. I didn't learn about post-prandial blood sugar spikes were recently. Anyway, I started pre-cooking and cooling pasta, potatoes, and rice, as well as freezing bread, and discovered that, whatever else it does, it's a big time saver when I'm prepping meals.

Dr. Alex - Thank you for the safety tips about rice. I've been counter cooling and fridge storing it in the rice cooker pan ... thankfully without adverse events. But there's no point in continuing to take stupid risks. I will also be defrosting our sourdough before toasting it, so we get that extra bit of benefit. I love knowing all this science about my food!

@GCNCaroline 2 weeks ago

You always offer such important information, and in such a calming and easy way for the average layperson to grasp. Well done, and thank you.

@merlion6613 10 days ago

I got fed up with not being able to find decent bread with minimum ingredients so started to bake my own recently. I used to keep shop- bought bread in my freezer for convenience. Since I started baking my own, I stopped doing that. I just put my freshly baked one into freezer now - hope I remember to take it out first thing in the morning 😂

@AF-ke9by 2 weeks ago (edited)

COOLING TIP for rice, potatoes, lentils, beans, and pasta: Spread it out on a sheet pan for 20-30 minutes to let most of the heat release, then put the pan in the freezer for 30-60 minutes to finish cooling it FAST. After that, put it into a storage container and freeze or refrigerate as you prefer.

@DPB1947 2 weeks ago

Thank you for another excellent video, Dr Alex!
When I took a mandatory food safety handling course for a small food business I was starting up, the instructor emphasized "the danger zone" for cooked foods: generally between 150 degrees and 50 degrees Fahrenheit. He advised that it is in this range that bacteria thrive.
As a result, when I go to large family dinner events or other catered events where food is sitting out there, I am always very cautious. At home, I place any leftover cooked foods that I am not eating immediately into a glass container with a lock seal on top. This way, it is not exposed to airborne bacteria, and as it cools the sealed container draws a bit of a vacuum. Then after the sealed food has cooled considerably, I place it in the fridge or freezer away from other stored foods to get it out of that danger zone as quickly as possible. I would welcome your feedback or other commenters' feedback on this method. Thanks again!

@catjane358 2 weeks ago

I find that I've been 'making' resistant starch for years! I batch cook, usually six to eight meals in a go, and freeze them all. I also freeze my bread as, as a single person, I only have one or two slices a day, on average. Batch cooking, if you can do it, is the way to go, not just for resistant starch but also for budget, time spent cooking, and convenience. Cottage pie, lasagne, curries, chilli, briam, you name it! I make soups too, with potato in for thickening, and freeze them.

@juliew3740 2 weeks ago

I make my own sourdough bread. I used to worry because it was a much heartier bread than anything I could buy. I use a rye, whole wheat and white mixture and it is a lovely dense loaf with a good chew. I don’t worry about it being different nowadays because I like the taste and texture l get so much more than from a store bought loaf. Plus I know exactly what I put in it. It also goes into the freezer and now I know it’s a good practice, not just for my wallet but for my body, as well. Thank you for talking about this topic. I understand it better now.

@bobfry5267 2 weeks ago

Dump your rice into cold water and then drain it. Now put it in the fridge.

@peterjaycocks114 2 weeks ago (edited)

The best way to bring down the temperature of cooked rice quickly is to spread the rice on a clean large flat baking tray.

@lorrainethompson5874 12 days ago

This is really interesting. Thanks Alex. Im trying to get my head round how, for generations in the UK, we ate little other than potatoes, porridge and a few veg/meat and virtually no-one was overweight or lacking in energy.

@TheCatlady63 2 weeks ago

I have been freezing bread for years even before I knew it was more healthy to do so.

@joetrafecanty2931 7 days ago

Your advice on food has changed my life completely. Because I now have a complete understanding from a trusted professional about how these foods affect my glucose. My diabetes my cholesterol etc I recently had a Libre
Blood glucose monitor installed on my arms, and it told me and verifies everything you have said about foods instantaneously. This helps me greatly because I can see the numbers instantly and find out what's causing all my health problems. Thank you so much for your nutritional and medical advice

@augiemusky 2 weeks ago

watching from the western part of Canada. Just been informed that I'm on the edge of diabetes. This information helps me

@MealCode8 2 weeks ago

Concise, succinct, and easy to understand. Truly useful. Thank you very much.

@menchuph8490 13 days ago

Excellent explanation. I don't think it can get any clearer than this! P.S. To cool down a starchy food faster, especially in warmer climates and regions, an electric fan might help.

@РусланДобрый-ч9у 2 weeks ago

Can’t understand why the book called The Draveny Method by Paul Draveny isn’t talked about more. Apparently this guy worked with famous athletes before suddenly disappearing from public view.