Is Reheated Pasta Really Less Fattening?

The latest nutrition story I came across this week centers on the idea that cooling and then reheating pasta makes it “less fattening” and “better for you” than pasta that’s only been cooked once.

The story comes from an experiment on the BBC TV show Trust Me, I’m a Doctor. Here’s a snippet from the article that describes what happened:

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Cooking pasta and then cooling it down changes the structure of the pasta, turning it into something that is called “resistant starch”.

It’s called “resistant starch” because once pasta, potatoes or any starchy food is cooked and cooled it becomes resistant to the normal enzymes in our gut that break carbohydrates down and releases glucose that then causes the familiar blood sugar surge.

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%.

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.
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So what does this “extraordinary result” mean for you?

It means absolutely nothing.

I once wrote that “the media passion for pointless non-stories means that the vast majority of what passes for health and fitness news is either completely meaningless or plain stupid. Most of it is a complete waste of your time.”

And this is exactly the type of thing I was talking about.

First of all, the title of the article is more than a little misleading. It’s based on the presupposition that pasta is fattening, which it isn’t.

No single food, in and of itself, is fattening.

Rice isn’t fattening.

A Big Mac isn’t fattening.

Custard creams aren’t fattening.

What’s fattening is consistently eating too much food relative to your energy needs.

What about the idea that cooking, cooling and then reheating pasta will make it better for you?

We know from other studies that putting starchy foods through several heating/cooling cycles can increase their resistant starch content [4]. We also know that supplementation with resistant starch can improve insulin sensitivity and blood sugar control following a meal [3].

So the finding that reheated pasta reduces the rise in blood sugar levels by 50% relative to regular cooked pasta is not an entirely surprising one.

However, blood sugar levels were measured for only two hours. When you bump up the amount of resistant starch in a meal, it slows down the rate at which carbohydrate is digested. This means that the disposal of glucose after a meal will take longer.

In other words, the difference in blood sugar levels between the cooked and reheated pasta would be considerably less if measurements had been taken over four hours rather than two.

What’s more, the amount of resistant starch you get from pasta is relatively small.

Even if you cool and then reheat pasta, you’ll get just a few extra grams of resistant starch relative to regular cooked pasta.

What will this small amount of extra resistant starch do for you?

Unfortunately, not very much at all.

Even in subjects given large amounts of resistant starch (40 grams per day for 12 weeks), there was no effect on weight loss [1]. Much the same result has been shown in other studies using 15-30 grams of resistant starch [2].

If taking 40 grams of resistant starch every day has no impact on weight loss, then the tiny amount of extra resistant starch that you get from reheated pasta isn’t going to do much.

Pasta is not fattening.

Reheated pasta isn’t any less fattening.

All the faffing around involved in cooking pasta, putting it in the fridge and then heating it up again is a waste of your time and money.

The only conceivable way in which reheated pasta will help you lose weight is if it tastes so bad that you end up throwing it in the bin.

References
1. Johnston KL, Thomas EL, Bell JD, Frost GS, Robertson MD. (2010). Resistant starch improves insulin sensitivity in metabolic syndrome. Diabetic Medicine, 27, 391-397
2. Maki KC, Pelkman CL, Finocchiaro ET, Kelley KM, Lawless AL, Schild AL, Rains TM. (2012). Resistant starch from high-amylose maize increases insulin sensitivity in overweight and obese men. Journal of Nutrition, 142, 717-723
3. Robertson MD, Bickerton AS, Dennis AL, Vidal H, Frayn KN. (2005). Insulin-sensitizing effects of dietary resistant starch and effects on skeletal muscle and adipose tissue metabolism. American Journal of Clinical Nutrition, 82, 559-667
4. Yadav BS, Sharma A, Yadav RB. (2009). Studies on effect of multiple heating/cooling cycles on the resistant starch formation in cereals, legumes and tubers. International Journal of Food Sciences and Nutrition, 60, 258-272