Cooking pasta or rice, then chilling it overnight in the fridge before reheating changes the starch's structure in a way that softens the blood sugar spike that follows. Multiple randomized trials point in the same direction.
This is the resistant starch effect. When cooked starch cools, some of the amylose chains reorganize into tight double helices that digestive enzymes struggle to break down.
Instead of being absorbed as glucose in the small intestine, that portion passes into the colon, where gut bacteria ferment it. The result is less sugar reaching the bloodstream after a meal.
What the chickpea pasta trial found
A randomized crossover trial published in October 2024 in the journal Metabolites tested 100 percent chickpea pasta in 12 healthy adults. Each participant ate the pasta twice, once freshly cooked and once cooled for 24 hours at 4°C and briefly reheated.
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The resistant starch content roughly doubled after cooling, rising from 1.83 to 3.65 grams per 100 grams of pasta. The glycemic index fell from 39 for the fresh version to 33 for the cooled and reheated one.
The area under the post-meal glucose curve was also significantly lower after the cooled portion (p = 0.0022). Both values already sit in the low-GI range, but the trial suggests cooling nudges an already gentle food further down.
The rice study in people with type 1 diabetes
A 2022 study in Nutrition and Diabetes ran a parallel experiment with long-grain white rice in 32 adults with type 1 diabetes. Cooled and reheated rice contained 11.96 grams of resistant starch per 100 grams, compared with 7.52 grams in the freshly cooked version.
After the cooled meal, peak blood glucose was significantly lower than after fresh rice, 9.9 versus 11 mmol/L (p = 0.0056). The maximum glycemic rise dropped from 3.9 to 2.7 mmol/L.
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The authors flag one important caveat. Because the meal releases less glucose, the standard mealtime insulin dose can push blood sugar too low. Hypoglycemic episodes were more frequent after the cooled rice in that trial. Anyone with diabetes considering this change should discuss insulin timing and dose with their doctor.
The practical protocol
Cook the pasta or rice as you normally would. Cool it in the fridge for at least 12 hours. Overnight is convenient. Reheat to serving temperature when you eat it.
Reheating does not undo the effect. The retrograded starch structure that forms during cooling is stable at ordinary cooking temperatures, which is why the cooled and reheated portions in both trials still delivered a lower glucose response than the fresh ones.
In the chickpea pasta trial, the cooled and reheated version scored similarly to fresh on appearance, taste, smell and texture, so the trade-off at the plate is small. The starch that reaches the colon also feeds gut bacteria that produce short-chain fatty acids, one of the reasons cooled starches are increasingly viewed as gut-friendly.
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Both trials were small, and cooling is not a substitute for the broader habits that shape blood sugar. Both studies used a 24-hour cooling window at 4°C, a condition an overnight stint in a standard home fridge meets.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.