Why Would Cooling Rice Make it Less Caloric?

Scientists suggest a new way to prepare rice that they say could help slow the worldwide obesity epidemic

One group of scientists says that they've figured out a way to make rice with fewer calories. A. Huber/U. Starke/Corbis

Fans of leftovers, listen up: refrigerating rice cooked with just a teaspoon of coconut oil could cut the amount of calories we absorb from it by up to 60 percent, according to a team of scientists from Sri Lanka.

The researchers, who recently made a presentation on the subject to the American Chemical Society, developed the new cooking method while seeking out “food-based solutions” to combat growing global obesity rates. And they deemed rice, which remains a mealtime staple in many countries where sedentary lifestyles are becoming more common, a good place to start.

As a type of carb, the starch in rice is broken down by our bodies into simple sugars, explains Michelle Roberts, health editor at BBC News. Those sugars get stored and then converted into glucose, which helps give us energy. But when the body has more glucose than it can use, that can add up to fat. Rice, however, has two types of starches—digestible and indigestible—and only the carbs our digestive system can absorb get broken down into sugars.

So the research team set out to find a way to make more of the starches in rice indigestible, which would then make it less caloric. And how can you do that? It all comes down to the preparation, they say.

If you simmer rice for forty minutes in a little bit of coconut oil, as the researchers recommend, the oil “enters the starch granules in the rice, changing their structure to be resistant to the enzymes that would normally break down the starch during digestion,” explains Alexandra Ossola over at Popular Science.

Then comes the key component: refrigeration. “The cooling is essential because amylose, the soluble part of the starch, leaves the granules during gelatinization,” said research team leader Sudhair A. James. “Cooling for 12 hours will lead to formation of hydrogen bonds between the amylose molecules outside the rice grains which also turns it into a resistant starch.”

The more resistant starch, the fewer calories we can absorb. The team notes that you can still re-heat the specially prepared rice without accruing any additional calories. (Whether it still tastes any good is a whole separate question.)

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