Could chilling rice and pasta help reduce blood sugar spikes?

A simple kitchen habit has recently become a talking point in wellness circles: cooking rice, pasta or potatoes, letting them cool in the fridge, and then reheating them before eating.

Why chilling your rice or pasta may change how your body digests it

Online nutrition influencers claim this process can lower calories and make carbohydrate-rich foods healthier. The explanation often cited is a chemical process called Retrogradation, which alters the structure of starch when cooked foods are cooled.

The idea is not entirely unfounded. But according to nutrition researchers, the science behind it is more nuanced than viral posts suggest.

Understanding starch

Most of the calories in foods like rice, pasta and potatoes come from starch. Starch itself is made up of two types of molecules: amylose and amylopectin.

Amylopectin is easily digested by the body and tends to raise blood sugar quickly. Amylose, on the other hand, digests more slowly and behaves more like fibre. This slower-digesting form is often referred to as Resistant starch.

When starchy foods are cooked, much of their resistant starch converts into forms that are easier to digest. Cooling them afterwards triggers retrogradation, a process in which some of that starch restructures itself back into a resistant form.

This means the body digests the starch more slowly, even if the food is reheated before eating.

What studies suggest

Research over the past decade has explored how this process affects blood sugar levels. Several small studies since 2015 have found that people who ate rice that had been cooked and cooled experienced lower post-meal blood glucose levels compared with those who ate freshly cooked rice.

These findings are generally accepted within nutrition science.

However, evidence that retrogradation significantly reduces calories is less clear.

According to David Ludwig, an endocrinologist at Boston Children's Hospital, cooling starchy foods does not meaningfully change their calorie content. What it may do instead is influence metabolism and appetite regulation.

Slower digestion means blood sugar levels rise more gradually. That matters because sharp spikes in blood sugar can trigger cravings later, making overeating more likely.

More stable blood sugar levels may also reduce the release of insulin — the hormone that signals the body to store excess energy as fat.

Is it worth doing?

While the cook–chill–reheat approach may slightly improve how the body processes carbohydrates, experts caution that it is not a magic solution for weight loss.

Walter Willett, professor of nutrition and epidemiology at Harvard T.H. Chan School of Public Health, notes that the benefits depend on consistency and may vary depending on the type of grain used.

Some varieties of rice and grains naturally contain less resistant starch, meaning cooling may have only a limited effect. Unfortunately, this information is rarely available to consumers.

Willett also points out that the process does nothing to restore nutrients lost when grains are heavily refined.

In other words, chilled pasta or rice may digest more slowly — but it does not replace the nutritional value of whole grains.

For most people, experts say the simplest approach remains the most reliable: choosing minimally processed grains, balancing carbohydrates with fibre and protein, and focusing on overall dietary patterns rather than individual food hacks.

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