Does Refrigerating Rice Reduce Carbs? The Science Behind Resistant Starch

November 19, 2025 •

2 min read

According to a 2015 study, cooked rice that was cooled and then reheated had 2.5 times more resistant starch than freshly cooked rice. This remarkable chemical change explains why refrigerating rice reduces the number of digestible carbohydrates your body absorbs from it.

Quick Summary

Cooling cooked rice transforms its starches into a type called resistant starch, which is not fully digested by the body. This process effectively lowers the amount of available carbohydrates and calories absorbed, providing health benefits similar to fiber.

Key Points

Not Carb Removal, but Transformation: Refrigerating cooked rice doesn't eliminate carbohydrates, but converts some of the digestible starch into resistant starch through a process called retrogradation.
Lower Glycemic Index: This conversion of starch results in a lower glycemic index for the rice, leading to a smaller and slower increase in blood sugar levels after a meal.
Benefits for Blood Sugar: The reduced blood sugar impact makes cooled rice a better choice for people managing diabetes or prediabetes.
Enhances Gut Health: Resistant starch acts as a prebiotic fiber, which feeds beneficial gut bacteria and promotes the production of beneficial short-chain fatty acids like butyrate.
Proper Cooling is Key: To increase resistant starch and prevent food poisoning, cooked rice must be cooled and refrigerated promptly within a few minutes after cooking.
Reheating Won't Undo the Effect: Reheating the cooled rice will not destroy the newly formed resistant starch, meaning you can still enjoy it warm and benefit from the change.

The Science of Starch Retrogradation

When rice is cooked, starch molecules absorb water and swell (gelatinization). Cooling cooked rice, especially in the refrigerator, causes retrogradation. During retrogradation, starch molecules re-crystallize into a structure more resistant to digestive enzymes. This modified starch passes into the large intestine, acting like dietary fiber.

The Impact on Digestible Carbs

Refrigerating rice doesn't remove carbs but makes a portion indigestible. This means fewer calories are absorbed, and blood sugar rises more slowly than with freshly cooked rice. This can be beneficial for managing blood sugar.

Enhancing Resistant Starch Formation

Cooking and cooling rice is effective for increasing resistant starch, but adding a small amount of fat like coconut oil during cooking can boost the effect.

Steps to Increase Resistant Starch:

Cook: Add a teaspoon of coconut oil per cup of rice when boiling water.
Cool: Cool cooked rice quickly and refrigerate for at least 12–24 hours.
Reheat: Reheating the rice later does not destroy the resistant starch.

Proper cooling and refrigeration are essential to prevent food poisoning from Bacillus cereus bacteria.

Resistant Starch vs. Digestible Carbs in Rice


Feature	Freshly Cooked Rice	Cooled & Reheated Rice
Starch Type	Easily digestible starch	Higher percentage of resistant starch (RS3)
Glycemic Index (GI)	High (e.g., GI of 78)	Lower (e.g., GI of 54)
Digestion Rate	Rapidly digested into glucose	Digested much more slowly
Blood Sugar Response	Causes a faster and higher blood sugar spike	Results in a smaller, more gradual blood sugar increase
Caloric Impact	Standard caloric absorption	Lower net caloric absorption
Effect on Gut Health	No significant prebiotic effect	Acts as a prebiotic, feeding beneficial gut bacteria

Beyond the Carbs: The Health Benefits

Increased resistant starch in rice provides benefits beyond reducing digestible carbs. Fermentation by gut bacteria produces short-chain fatty acids (SCFAs), like butyrate.

Benefits of Increased Resistant Starch:

Improved Gut Health: Butyrate supports colon cell health.
Better Insulin Sensitivity: Regular intake can improve the body's response to insulin.
Enhanced Satiety: Resistant starch helps you feel fuller, potentially aiding weight management.

Is Refrigerating Rice a Weight-Loss 'Hack'?

While it modestly reduces digestible calories and is good for blood sugar management, it's not a weight-loss miracle. Claims of up to 50% calorie reduction are not fully supported by research. Sustainable weight management depends on overall diet, exercise, and lifestyle.

Conclusion

Refrigerating cooked rice increases resistant starch, lowering its glycemic impact and reducing digestible calories. This makes rice a healthier option, especially for blood sugar control and gut health. This method is part of a broader healthy eating plan and works best with other nutrient-rich foods and a balanced lifestyle.

Visit Healthline for more detailed information on resistant starch and other foods.

Frequently Asked Questions

Refrigerating rice triggers a process called starch retrogradation, where the cooked starches recrystallize into a form that is resistant to digestion in your small intestine. While the total carb count remains the same, your body absorbs fewer of those carbs, leaving more for your beneficial gut bacteria to ferment.

You can eat the rice cold to reap the benefits of resistant starch. In fact, reheating it does not reverse the process, and cooled-then-reheated rice will still have a higher resistant starch content than freshly cooked rice.

Refrigerating cooked rice for at least 12 to 24 hours is recommended to allow for optimal resistant starch formation. Some studies show that longer refrigeration periods may continue to increase the resistant starch content.

The starch retrogradation process works for various starchy foods, including different types of rice. However, different varieties have different starch compositions (amylose vs. amylopectin), which can affect the final amount of resistant starch formed.

Yes, some research suggests that adding a teaspoon of coconut oil during the cooking process and then cooling the rice can further enhance the formation of resistant starch.

Yes, it is safe, but proper food safety measures are essential. You must cool the rice quickly after cooking and refrigerate it promptly. Do not leave cooked rice at room temperature for an extended period, as it can harbor Bacillus cereus bacteria.

The principle of starch retrogradation applies to other starchy foods as well. You can increase resistant starch in potatoes and pasta by cooking them and then cooling them in the refrigerator.