If you love rice, rotis, or other cereals but worry about their impact on blood sugar, here’s a surprisingly simple hack backed by science: cook them, cool them, and then eat them. This cooling process increases something called resistant starch — a powerful form of dietary fiber that can lower the glycemic index of your meals.
What Is Resistant Starch?
Resistant starch is a type of carbohydrate that "resists" digestion in the small intestine and reaches the colon largely intact. Unlike regular starch (which is broken down into glucose), resistant starch behaves more like soluble fiber — it's fermented by gut bacteria and offers a host of metabolic benefits.
Resistant starch is naturally present in foods like green bananas, cooked and cooled potatoes, legumes, and — importantly — cooked and cooled grains like rice and wheat.
The Science: How Resistant Starch Is Formed
When you cook rice, rotis, or any starchy cereal, the starch granules absorb water and gelatinize, becoming soft and digestible. But when you cool these foods, some of this starch undergoes a transformation called retrogradation — where starch molecules re-form into crystalline structures that are harder to digest. These restructured starches are classified as resistant starch (specifically RS3 type).
This transformation doesn’t require special ingredients or supplements — just time and a fridge.
How Much Cooling Is Enough?
Research suggests that:
- Cooling cooked rice or roti for 8 to 12 hours (ideally overnight in the fridge) can increase resistant starch content by 2x to 3x.
- Reheating (lightly warming, not overcooking) does not destroy the resistant starch — in fact, some studies show that cooling and reheating may enhance it further.
This means you can batch-cook your rice, refrigerate it overnight, and reheat portions the next day for a lower glycemic impact meal.
How It Impacts Glycemic Index (GI)
The glycemic index (GI) is a measure of how quickly a carbohydrate-containing food raises blood glucose levels. Foods with high GI (like white rice or white bread) cause quick spikes, while low GI foods are digested more slowly, resulting in a gradual blood sugar rise.
By increasing resistant starch:
- The GI of white rice can drop from ~70 to ~50–60, depending on the variety and cooling duration.
- Whole wheat roti may show a 10–15% improvement in post-meal blood glucose response after cooling and reheating.
- Even cereals like pasta, poha, or idli can benefit from this method.
This is particularly useful for people with diabetes, insulin resistance, or PCOS, or those trying to maintain stable energy and satiety.
How to Use This Hack at Home
- Rice: Cook, cool overnight, and reheat before eating. Works with white, brown, or parboiled varieties.
- Rotis / Chapatis: Make in advance, cool, and reheat on a tava or wrap in foil and warm in the oven.
- Other grains: Use the same trick with poha, sabudana, broken wheat, and even pasta.
Tip: Cook in larger batches to save time — this method is both healthier and convenient.
The Bottom Line
Cooling cooked grains before eating them is a simple, science-backed hack to improve your carbohydrate quality. It enhances resistant starch, which supports gut health, improves insulin sensitivity, reduces glycemic spikes, and keeps you fuller for longer.
So next time you're preparing rice or rotis, give them a rest in the fridge. Your gut — and your blood sugar — will thank you.