How to halve the calories in a bowl of rice

Rice is one of the most ubiquitous foods in the world – and as obesity levels rise, scientists have found a way to cook it that reduces the calories by half, says Roberto A. Ferdman

Rice is perhaps the most ubiquitous food in the world. In Asia, where an estimated 90 per cent of all rice is consumed, the pillowy grains are part of almost every meal. In the Caribbean, often mixed with beans, rice is a staple too. Even in Britain, where people eat a comparatively modest amount of rice, plenty is consumed.

Rice is popular because it's malleable – it pairs well with a lot of different kinds of food – and it's relatively cheap. But like other starch-heavy foods, it has one central flaw: it isn't that good for you. White rice consumption, in particular, has been linked to a higher risk of diabetes. A portion of the cooked grain carries with it roughly 200 calories, most of which comes in the form of starch, which turns into sugar and often, thereafter, body fat. But what if there were a simple way to tweak rice ever so slightly to make it much healthier?

An undergraduate student and his mentor, at the College of Chemical Sciences in Sri Lanka, have been tinkering with a new way to cook rice that can reduce its calories by as much as 50 per cent and even offer a few other added health benefits. "What we did is cook the rice as you normally do, but when the water is boiling, before adding the raw rice, we added coconut oil – about 3 per cent of the weight of the rice you're going to cook," says Sudhair James, who presented his preliminary research at National Meeting & Exposition of the American Chemical Society (ACS) earlier this month. "After it was ready, we let it cool in the refrigerator for about 12 hours. That's it."

To understand what's going on, you need to understand a bit of food chemistry.

Not all starches are created equal. Some, known as digestible starches, take only a little time to digest, are quickly turned into glucose, and then later glycogen. Excess glycogen ends up adding to the size of our guts if we don't expend enough energy to burn it off. Other starches, meanwhile, called resistant starches, take a long time for the body to process, aren't converted into glucose or glycogen because we lack the ability to digest them, and add up to fewer calories. A growing body of research, however, has shown that it might be possible to change the types of starches found in foods by modifying how they are prepared. At the very least, we know that there are observable changes when certain foods are cooked different ways. Potatoes, for instance, go from having the right kind of starch to the less healthy kind when they are cooked or mashed (sigh, I know). The process of heating and cooling certain vegetables, like peas and sweet potatoes, can also alter the amount of resistant (see: good) starches, according to a 2009 study.

And rice, depending on the method of preparation, undergoes observable chemical changes. Most notably, fried rice and pilaf-style rice have a greater proportion of resistant starch than the most commonly eaten type, steamed rice, as strange as that might seem.

"If you can reduce the digestible starch in something like steamed rice, you can reduce the calories," says Dr Pushparajah Thavarajah, a professor who is supervising the research. "The impact could be huge."

Understanding this, James and Thavarajah tested eight different recipes on 38 different kinds of rice found in Sri Lanka. What they found is that by adding a lipid (coconut oil in this case, because it's widely used in Sri Lanka) ahead of cooking the rice, and then cooling the rice immediately after it was done, they were able to drastically change its composition – and for the better. "The oil interacts with the starch in rice and changes its architecture," said James. "Chilling the rice then helps foster the conversion of starches. The result is a healthier serving, even when you heat it back up."

So far they have only measured the chemical outcome of the most effective cooking method for the least healthful of the 38 varieties. But that variety still produced a 10 to 12 per cent reduction in calories. "With the better kind, we expect to reduce the calories by as much as 50 to 60 per cent," said James.

The prospect of lower-calorie rice is a big deal. Obesity rates are rising around the world, particularly in the developing world, where people rely more heavily on cheaper food staples. China and India, which are already seeing rising obesity problems, are huge consumers of rice. Rice, of course, is not the sole cause of weight gain. But reducing the amount of calories in a cup of rice by even as little as 10 per cent could have an enormous impact for future generations. µ

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