Rise in blood sugar 30-50% less with reheated pasta than the same freshly cooked pasta?!

I heard this on a podcast today, and thought it was incredibly interesting and practical information. So often I see a headline with buzzwords about a new way to decrease glycemic load and its the same ol' obvious information. This was news to me, and I hope that by sharing it I teach someone else something new too!


Color me skeptical.

Regardless of their representation, a sample size of 10 subjects cannot possibly establish scientifically valid results that would allow any reasonable conclusions.

I think it would be more convincing with more subjects, but I wouldn't say it's completely scientifically invalid or that their conclusions are unreasonable. There have been studies done to determine the number of subjects required to get reasonable GI means... and ten is often good enough to get significantly relevant results. If your not TOO concerned with precision ;-).

There has been a lot of interest in what is called "resistant starch." This is starch which is essentially fiber as it cannot be digested in the small intestine and instead is digested through fermentation in the large intestine. And this fermentation results in the starch being converted to Short Chain Fatty Acids (yes dietary fat) which is then absorbed.

One way to make resistant starch is to cook the starch and then cool it. When served cold or at room temperature many of the starch molecules will have become bound during cooling in a way that they are resistant to digestion enzymes and hence act as resistant starch. It you want to try it with potatoes or pasta you may find it works and it may convert some non-trivial amount of the start to resistant starch. But I'm not clear that it converts most of the starch and it certainly doesn't convert all.

And I've not really seen much evidence that starch remains in a resistant state when reheated. I think the standard advice is that if you reheat it you break all the resistant starch back into digestible starch. I think the best advice is that you need to eat it cold (or room temperature).

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This is not a new subject, for years the DOC has had many discussions about cooled or even frozen pasta and I believe the results have been poor. There has been a massive amount of posts about how ? to eat Pasta without going high.

I think most would agree that Abstaining ...probably gives the best results...but where only human...

I can eat it without a horrible long lasting high if I limit my intake to under 2oz and hit it with a big Sq wave bolus but I generally just skip the pasta...2oz of pasta just looks rather anemic sitting there in the middle of a big dinner plate.

I find this interesting. I can eat an Amy's Frozen Lasagna and dose for the 37g of carb and not go high. I never understood why but was very pleased. Maybe this is the explanation.


I think what is different about this and previous talk of resistant starches is that it seemed to still have (and a better effect) on blood glucose after being reheated. Implying the starches are not reconverted when heated and don't have to be eaten cold to get the effect.

This was a study done at the University of Surrey. They actually found that reheating the cold pasta after sitting overnight in the fridge caused less blood glucose rise than just eating it cold.... claiming approx. 50% less glucose rise. I logged in today just for this purpose, to find out if anyone had tried it and what their experience was. We have had great results with giving our Type 1 child (now teen) Ancient Harvest Quinoa Pasta, no spikes and we had to bolus a lot less for the pasta. She was able to have a two cup serving and charge 50 grams carbs. They must have changed the formula; the pasta cooks up very mushy and flat. Therefore, I am very interested in an alternative. Has anyone tried cooling pasta overnight, reheating it. If so, what has your experience been? And did you bolus normally, combo bolus or even reduce the bolus. Obviously, it would be better to eliminate pasta from the diet altogether but that ain't happening as she demands this food. Lasagna or ziti with regular pasta, never a problem. Has anyone tried this?

Here's one of the articles I found on the subject: I know it's better to abstain from pasta totally but for those who won't give it up:
Power Daily diabetes, diet free life, pasta, resistant starch October 17, 2014
Cooked Pasta

Imagine cooking pasta, letting it cool and then reheating it and reducing the blood sugar impact up to 50 percent opposed to consuming pasta after cooking it initially. According to scientist Dr. Denise Robertson, from the University of Surrey, if you cook and cool pasta down then your body will treat it much more like dietary fiber, creating a smaller glucose peak, helping feed the good bacteria that reside down in your gut and absorbing fewer calories.

The research demonstrates that cooking pasta changes the structure of the pasta, burning it into something called “resistant starch”. When most people hear “starch” they are quick to avoid it at all cost, but “resistant starch” is proving itself to be quite helpful. Case in point, most people are aware that the starch in potatoes, cereals, and baked goods digests very rapidly. Other starchy foods, such as beans, barley, or long grained brown rice, are digested more slowly, and cause a much slower and lower blood sugar rise. Resistant starch actually goes all the way through the small intestine without being digested at all. In this way, it is more like fiber, and in some cases is classified and labeled as fiber.

In this study, Dr. Chris van Tulleken roped in some volunteers to do the tests. The volunteers had to undergo three days of testing in all, spread out over several weeks. On each occasion they had to eat their pasta on an empty stomach.

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.

On each of the days they also had to give blood samples every 15 minutes for two hours, to see what happened to their blood glucose as the pasta was slowly digested.

The outcome demonstrated that eating cold pasta led to a smaller spike in blood glucose and insulin than eating freshly boiled pasta.

It gets better

To the surrise of the researchers, they found something that they’d never 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%.

This certainly suggests that reheating the pasta made it into an even more “resistant starch”. It’s an extraordinary result and one never measured before.

Denise is now going to continue her research – funded by Diabetes UK – looking at whether, even without other dietary modifications, adding resistant starch to the diet can improve some of the blood results associated with diabetes.

Source: BBC News

I have to caution you, this is what I term a "clinical observation." This was just a couple of people that makes the result entirely explainable by chance. You need a lot more people (and preferably diabetic) to have any confidence in the result.

ps. In fact for non-diabetics, the cool pasta meal may have actually generated a modest insulin response while the reheated pasta generated a huge response. If that is the case the blood sugar rise is irrelevant.

The doctor says it makes the white pasta equal whole grain, well I can say 100% that whole grain carbs are still carbs and that I have to cover with the same amount of insulin. Then the Doc says the cooled and reheated pasta has the same amount of calories but digestion is slowed down,this may be good for a T2 or a none PWD but for a T1 like me I'm looking for relatively fast acting carbs that match my insulin curve. Pasta already creates a slow long lasting spike in BG that out lasts my insulin just like pizza or a big serving of protein. I cannot see any benefit for a T1, from personal experience I can say with 100% confidence that cooling down and reheating my pasta does not change it into a go to "great choice" food for me...;-)...JMHO

I just did a test on Ronzoni thin spagetti, cooled in fridge overnight and reheated in a little Prego sauce. Pasta does not match insulin duration, as someone mentioned. Not claiming pasta is a good food choice..... just want to know how to bolus for it. She does and will eat pasta. I am fairly impressed with the results. If she has lasagna or baked ziti with regular pasta, no problem. It is the plain pasta with sauce, pesto or butter that causes issues. I gave her two cups of cooled and reheated pasta with sauce and 15 grams of grapes. Basically, I treated it as if I was bolusing for Quinoa pasta. I charged 60 grams for the two cups of pasta (just like quinoa) and 15 for the grapes. I bolused 35 grams for the pasta and 15 grams for the grapes up front (50 grams). Three and a half hours after eating when she came back home she was 200. Bolused four units for the other half of the pasta. Two hours later 165, three hours later 119 and there was still insulin on board, So, for her, it will require combo bolus, like quinoa, probably two hours after the initial bolus we should give the other half. The timing was off because she went out with friends, so did not do the two hour postprandial check. Regular pasta that has not been cooled and reheated is an all night high affair that does not come down despite repeated boluses. This requires tweaking but it can be done.

P.S. Two cups of pasta is 80 grams. This pasta is like the quinoa pasta, where you have to bolus less for it. I only bolused 60 for it. Each person will have to test for themselves because what works for one may not work for another.

An update to my earlier post: She eats pasta about three times a week. The cooling down and reheating of the pasta (FOR HER) did result in better post-prandial blood sugars. BUT, two cups of pasta (80 grams) required the full bolus for the 80 grams, not a lesser bolus like quinoa pasta. I did pasta (40 percent bolus) with 15grams of fruit (100 percent bolus). Two hours later I bloused for the other 40 percent. Blood sugars back to normal, good.

If you put cooked pasta in a colander and pour heated water over it you are basically washing off any residual carb/pasta powder that might be left sticking to the exterior of the pasta. Thus lowering how the load.

Old wives tale? Any studies to show how much?

I would submit it's such an insignificant amount as to be a complete waste of time...it's pasta after all.

I have tried this not only with pasta & rice but also authentic NY pumpernickel bagels and pretzel rolls. Freezing & reheating reduces the spike to my BS by at least 30% and up to 50% or more if I eat something high in protein, fiber or fat immediately before hand.
I even went to PF Chang’s and started with the spare ribs appetizer before eating brown rice & fried rice with shrimp & chicken. Normally my BS would skyrocket to 250-300 but just eating the spare ribs before the main courses my BS only went to 175.
In the case of the very large NY bagel (Essa Bagel). Normally if I eat a toasted bagel from room temp with butter or cream cheese my BS goes from 90 to 180-190 but when I thaw a frozen bagel for 30 seconds in the microwave, slice it in half, toast it & add butter or cream chees then my BS only goes to 140-150 max but if I eat bacon, sausage, hard boiled eggs, scrambled eggs, etc., just before the bagel then my BS only goes to 120 max.

@brboyer ,

I’m not sure statistically meaningful results are very important here. If each interested individual tries it for himself, and the ones who get consistently good results (if any) continue to use it, what’s wrong with that?

Some may gain, nobody loses.

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