This 2-step hack to reduce the calories in white rice is going viral — and dietitians say it actually works

White rice can be part of a healthy diet, but it's not the most nutritious grain out there. That's why a hack meant to reduce the calories and carbs in white rice is getting widely shared on social media. All you have to do is cook rice, cool it in the fridge or freezer, and reheat it.

But does this rice hack really work or is it all hype? The experts TODAY.com spoke with say it actually does.

There's a few scientific elements at play behind this rice hack — namely that rice is made up mostly of starch, and cooking the rice changes the starch at the molecular level, as does cooling it down once it's cooked.

The cooling process makes the starch in the rice harder to digest, so the body takes in fewer calories and carbs when eating the rice that's been cooked and then cooled. But don't worry, you don't have to eat the rice cold to reap these benefits (though cooling it and heating it again does change its texture).

Read on to learn what experts say about how this rice hack works, the health benefits, risks and more.

Rice hack going viral on social media

Numerous accounts on TikTok and Instagram have posted about this rice hack, which is surprisingly easy to try:

• Cook your white rice.

• Pop it in the refrigerator overnight.

• Reheat it the next day.

The idea is that the cooling process increases the amount of a gut-healthy carbohydrate called resistant starch, which the body cannot digest. As a result, eating this rice with more resistant starch means consuming fewer calories and carbs, and less of a blood sugar spike.

Some influencers even claim the hack can slash calorie absorption from white rice in half, though the research doesn't quite back this exact amount up, the experts say.

What is resistant starch?

White rice is composed mostly of starches, which are complex carbohydrates made up of glucose molecules joined together by bonds, Grace Derocha, registered dietitian and spokesperson for the Academy of Nutrition & Dietetics, tells TODAY.com. (Glucose is a type of sugar and your body's main source of energy.)

"When we eat (starch), we have digestive enzymes that break it down into simple sugars that we can absorb," Darrell Cockburn, Ph.D., associate professor of food science at Penn State University, tells TODAY.com. This causes blood sugar to rise.

There are several types of starches, which are digested differently, Cockburn notes. These include rapidly-digestible starch, slowly-digestible starch and resistant starch.

Resistant starch is a type of carbohydrate that the body cannot digest. “They are called 'resistant' because they resist digestion in the small intestine. Instead, it moves into the colon (large intestine), where it’s fermented, creating short-chain fatty acids that feed healthy bacteria in the gut," Frances Largeman-Roth, registered dietitian nutritionist and author of “The Carb Lover’s Diet,” tells TODAY.com.

This means resistant starch acts like a dietary fiber, says Cockburn. In addition to feeding the microbes in the gut, resistant starches slow down sugar production and absorption, which means they do not spike blood glucose as much as other starches.

Resistant starches are linked to a number of health benefits, from boosting gut health and lowering blood sugar to preventing constipation and helping you feel full. "Resistant starch is plentiful in a variety of foods, like legumes and beans, whole grains, uncooked potatoes, and unripe bananas," says Derocha.

Cooling cooked rice means more resistant starch

Cooling and reheating rice will increase the resistant starch content, which affects its nutritional value, experts say.

Cooking food typically destroys the natural resistant starches. "When you have hot, cooked rice out of the pot, it has what we would call a 'loose structure' of the carbohydrate, so the glucose molecules are loose and digestible," Derocha explains.

If you eat freshly cooked rice right away, the body can break down these starches fully and use all of the carbohydrates, which will increase blood sugar. "Cooked starches ... can raise blood glucose levels almost as well as pure sugar because our digestive enzymes are so good at breaking it down," says Cockburn.

Over time, particularly at cooler temperatures, resistant starch can reform in some foods. “When you cook the rice and cool it in the refrigerator, what you’re doing is tightening those molecular bonds (so) they’re more resistant to digestion ... which builds up the resistant starch,” says Derocha.

The reformed resistant starch is more heat-resistant than the original resistant starch, "so reheating it does not usually destroy it," Cockburn adds.

The process where starches rearrange into a tighter structure as they cool, called retrogradation, also occurs with other starchy foods like pasta and potatoes, says Largeman-Roth.

In a 2015 study published in the Asia Pacific Journal of Clinical Nutrition, researchers in Indonesia compared the resistant starch content of freshly cooked white rice to cooked white rice that had been cooled at 4 degrees Celsius (39 degrees Fahrenheit) for 24 hours and then reheated. The reheated rice had about two and a half times more resistant starch than the freshly cooked rice.

Rice hack leads to fewer carbs and calories

Cooked, cooled and reheated rice has more resistant starch, so it contains fewer carbs available for the body to absorb, which also decreases the number of calories the body will take in.

That said, the exact amount by which this hack will lower the carbs and calories in white rice is not clear, the experts say. “Unless you’re in a laboratory testing, you don’t know, and that’s the hard part for people who are counting their carbs," Derocha explains.

In a 2022 study published in the journal Nutrition & Diabetes, researchers found that for every 100 grams of cooled rice, there are about 5 fewer grams of digestible carbohydrates compared to the same portion of fresh cooked rice.

Largeman-Roth estimates that cooked and cooled rice has about 10-15% fewer calories than freshly cooked rice.

Can this rice hack help with weight loss?

Research suggests eating foods with resistant starch may help weight loss goals, registered dietitian and TODAY.com nutrition editor Natalie Rizzo says.

For instance, one randomized controlled trial with 37 participants found that resistant starch alters the gut microbiome to inhibit fat absorption, which may promote weight loss. The same results have also shown in animal studies.

However, some earlier research was inconclusive regarding the impact of resistance starch on weight loss goals. So, although the newer research is promising, more is needed to make any sweeping claims about resistant starch and weight loss.

Is cooled and reheated rice healthier?

Yes. If properly cooled and stored, cooked white rice that is reheated can be healthier than freshly cooked rice.

“You’re getting a double benefit. ... Not only are you cutting out some of the carbs so your blood sugar doesn’t raise as fast, (but) you now have this resistant starch that works like fiber to feed good bacteria in the gut,” says Derocha.

Adds Largeman-Roth: “It also means that you’ll likely feel more full from the cooked and cooled starches.”

Some research also suggests that resistant starches may help lower the risk of colorectal cancer in some people.

While increasing resistant starch in the diet can be beneficial for anyone, Derocha says the hack can be helpful for people who eat white rice regularly but also need to watch their carb intake or blood sugar, as it reduces the amount and speed at which white rice raises a person’s blood sugar. Derocha, who is Filipino-American, adds her family has used this hack “forever.”

A 2017 study from researchers in New Zealand published in the journal Nutrients showed that reheating cooked and cooled rice may reduce the risk of Type 2 and gestational diabetes in the long-term.

The 2015 study out of Indonesia also concluded that white rice that has been cooled for 24 hours and reheated can be recommended for diabetic patients as part of their everyday diet.

“More studies need to be done to fully determine the health benefits; however, the lower spike in blood glucose and increased food for healthy gut microbes is likely to lead to health benefits,” says Cockburn.

In any case, the experts emphasize that people with diabetes should talk to their doctor and carefully monitor their carbohydrate intake and blood glucose levels.

Freshly cooked white rice can also be a part of a healthy diet in moderation, the experts note. "But if you’re trying to reduce your calorie intake and you don’t mind the flavor or texture of reheated rice, go for it,” says Largeman-Roth.

Additionally, Derocha recommends pairing rice with other foods that provide fiber, protein, and micronutrients, such as beans, fish, tofu, leafy greens, squash and other vegetables.

Downsides of cooling and reheated rice

There are some downsides of cooling and reheating rice, the experts note. First, it can compromise flavor and texture. "I think freshly cooked rice is always going to taste the best,” says Largeman-Roth.

Common mistakes while storing leftover rice can also increase the risk of food poisoning. Bacteria such as Bacillus cereus thrive in cooked starchy foods, like rice, and multiply rapidly when it's improperly cooled or left out at room temperature. That's why food poisoning with B. cereus is often called "fried rice syndrome."

Always refrigerate cooked rice within two hours, and make sure the fridge is set to 40 degrees Fahrenheit or cooler. "Don't put the whole hot rice cooker into the fridge ... put it in shallow containers so it cools faster," says Derocha. And reheat the rice until it reaches an internal temperature of 165 degrees Fahrenheit, per the USDA.

In general, try to keep cooked foods out of the "danger zone" of 40 degrees to 140 degrees Fahrenheit. After about three or four days, leftover rice should be thrown out. You can also store cooked rice in the freezer, which lasts longer.

This article was originally published on TODAY.com