MOST Malaysian households have a pot of leftover rice that ends up in the fridge, destined for tomorrow's nasi goreng.
Now imagine being told that yesterday's cold, forgotten rice might actually be a little better for you than the fresh, steaming bowl you just cooked.
Does keeping rice in the fridge really make it healthier to eat?
Verdict:
TRUE
As strange as it sounds, there is real science here, and it comes down to something called resistant starch.
When you cook rice, the heat and water cause its starch granules to swell and soften in a process called gelatinisation.
This is what makes hot, fresh rice so easy to digest.
Unfortunately, "easy to digest" also means your body breaks it down into glucose quickly, sending your blood sugar on a rapid climb shortly after your meal.
Here is where the fridge works its quiet magic.
When cooked rice is cooled, the starch molecules begin to rearrange themselves into tightly packed crystalline structures, a process known as retrogradation.
These reorganised structures become resistant to digestion, which is why they are called resistant starch.
Your digestive enzymes simply cannot break them down efficiently, so they pass through your small intestine largely intact, behaving much more like dietary fibre than like ordinary starch.
The effect is measurable. A 2015 randomised controlled study published in the Asia Pacific Journal of Clinical Nutrition compared freshly cooked white rice against rice that had been cooked, refrigerated for 24 hours and then reheated.
The cooled and reheated rice contained about 2.5 times as much resistant starch as the fresh rice, and when 15 healthy adults ate it, they showed a significantly lower blood glucose response.
A 2022 study published in the journal Nutrition and Diabetes went further, testing the effect on people with Type 1 diabetes.
It found that eating rice that had been cooled for 24 hours and then reheated produced a significantly lower peak in blood glucose compared to freshly cooked rice.
The crucial detail, and the reason your everyday leftover rice qualifies, is that the resistant starch survives reheating.
So the rice does not need to be eaten cold straight from the fridge like some kind of penance.
You can warm it back up and still keep much of the benefit.
For Malaysia, where rice is not so much a food as a way of life, this is more than a fun science fact.
Malaysia holds the unwelcome title of the country with the highest prevalence of diabetes in South-East Asia, with about one in five Malaysians recorded as diabetic in 2024.
South-East Asians also eat a lot of white rice, with the region recording a median consumption of around 239g per day, among the highest of any region studied in the large international research on rice and diabetes.
Anything that gently lowers the blood sugar impact of the national staple is worth knowing about.
Now for the BUT, because there are several worth keeping in mind before you start meal-prepping vats of rice.
First, the effect, while real, is not dramatic enough to turn white rice into a health food.
Cooling reduces the blood sugar spike, but cooled-then-reheated white rice is still white rice. It is not suddenly the nutritional equal of brown rice, which retains the fibre, vitamins and minerals stripped away during milling in the first place.
Second, the benefit depends on doing it properly.
The research points to cooling in the refrigerator for a good stretch, ideally around 24 hours, not simply leaving rice out on the counter for a couple of hours.
Which brings us to the most important caveat of all.
Cooling rice for health benefits must never come at the expense of cooling it safely.
Cooked rice can harbour a bacterium called Bacillus cereus, whose spores survive cooking and can multiply rapidly if rice is left standing at room temperature.
This is the culprit behind what is sometimes called fried rice syndrome.
To stay safe, rice should be cooled quickly and refrigerated within a couple of hours of cooking, stored properly, and reheated thoroughly.
Leaving rice sitting out overnight to develop resistant starch would be a spectacularly bad trade, swapping a small metabolic benefit for a genuine risk of food poisoning.
So the verdict holds. Cooling cooked rice really does increase its resistant starch content and modestly lowers its blood sugar impact, and the benefit survives reheating.
Just do it in the fridge, do it promptly, and do not mistake yesterday's nasi goreng for a health tonic.
It is a small, sensible bonus, not a miracle.
Sources:
1. https://pmc.ncbi.nlm.nih.gov/
2. https://www.nature.com/
3. https://apjcn.nhri.org.tw/
