Does Cooling or Reheating Rice Affect Blood Sugar?
This isn't a myth — cooling cooked rice before eating it (even after reheating) measurably softens its effect on blood sugar. Here's what the actual research found.
When rice is cooked and then cooled, some of its starch reorganizes into a form called resistant starch, which digests more slowly and raises blood sugar less than the same rice eaten fresh. This has been studied directly, including in people with diabetes, and the effect is real.
What the research found
- A clinical study found that rice cooled for 24 hours at 4°C and then reheated had meaningfully more resistant starch than fresh rice, and produced a lower glycemic response in healthy adults.
- A study in people with type 1 diabetes specifically found a significantly lower maximum glucose rise after eating cooled-and-reheated rice compared with fresh rice.
- A separate study estimated the glycemic response from cooled-and-reheated rice was roughly 20-35% lower than fresh rice, depending on the rice variety used.
The research specifically tested rice that was cooled, refrigerated, and then reheated before eating — the resistant starch effect persists through reheating. You don't have to eat cold rice to benefit from this.
How to actually use this
- 1Cook rice as usual, and if convenient, let it cool and refrigerate it for a few hours or overnight rather than eating it immediately.
- 2Reheat it normally before serving — the benefit doesn't require eating it cold.
- 3This works well for meal prep: rice made a day ahead and reheated may have a gentler effect than rice eaten straight off the stove.
A 20-35% softer glycemic response is meaningful, but it doesn't cancel out the effect of a large portion. Portion size is still the bigger lever — this is a useful addition to good portion habits, not a replacement for them.
“The rice doesn't change what it's made of — but giving it time to cool changes how your body breaks it down.”
A quick food-safety note
- Cool cooked rice reasonably quickly (within about an hour or two) before refrigerating, rather than leaving it out for a long stretch at room temperature.
- Reheat it thoroughly until hot all the way through before eating, and avoid reheating rice more than once.
Log a meal with freshly cooked rice, then a similar meal later with rice that was cooled and reheated, and compare your readings.
Frequently asked questions
Do I need to eat rice cold to get the resistant starch benefit?
No — research on this specifically tested rice that was cooled, refrigerated, and then reheated before eating. The benefit doesn't require eating cold rice.
How much does cooling and reheating actually lower the blood sugar effect?
One study estimated roughly 20-35% lower glycemic response compared to freshly cooked rice, though the exact amount varies by rice variety and how long it was cooled.
Does this mean I can eat more rice if I cool and reheat it first?
Not really — it softens the effect of a given portion, but it doesn't cancel out the effect of eating significantly more rice. Portion size still matters just as much.
Related reading
Can People With Diabetes Eat Rice?
Rice can raise blood sugar because it contains carbohydrate, but many people with diabetes can still include it in a balanced meal.
How Much Rice Can a Diabetic Eat?
A commonly used starting point is about half a cup of cooked rice per meal — but the cup, the rice, and the rest of the plate all change what that actually means.
Brown Rice vs. White Basmati Rice: Which Is Better for Diabetes?
Brown basmati generally has a lower glycemic index than white basmati, mostly thanks to fiber. It's a real advantage, not a dramatic one.
Does Cold or Reheated Roti Affect Blood Sugar?
You may have heard that cooling rice changes how it affects blood sugar. Something similar happens with roti — just to a smaller degree.