Good news for those who meal-prep: Not only is it time-saving, it might be healthier than you think. As it turns out, chilling certain foods before eating them amps up their benefits.
When rice, pasta, potatoes, or oats cool, their starch changes into something called “resistant starch”—a fermentable fiber that has been linked in numerous studies to more stable blood sugar, longer satiety, and happier intestinal flora.
For those who love a bit of nerdy nutritional info, here’s a little more about resistant starch: Unlike other carbohydrates that break down into sugar, it passes through to the colon, where it eventually produces short-chain fatty acids called butyrate, which is considered the ultimate for a healthy intestinal barrier. Because this starch “resists” being digested in the small intestine and ferments in the large intestine, it also acts as a prebiotic that feeds beneficial gut bacteria.
But the healthy cool-down effect also extends beyond our favorite carbs: studies show that polyphenols and antioxidants in some vegetables are better preserved or even enhanced when they are first heated and then cooled again.
Seven foods that are healthier cooled
#1 White rice
Several studies show that rice that has been cooked and cooled completely in the fridge contains significantly more resistant starch than freshly-cooked rice. After just twelve hours in the fridge, the proportion can increase many times over and has been shown to significantly lower increases in blood sugar.
#2 Pasta
Pasta also undergoes the same starch shift when chilled. A nutritional study showed that after 24 hours of cooling and subsequent gentle reheating, cooked pasta has significantly slower starch digestibility than freshly prepared pasta. This less rapidly available starch may also lead to a milder rise in blood sugar after eating.
#3 Oats
Oats are already very healthy. The grain is rich in beta-glucans, which clinical studies have repeatedly linked to better blood sugar regulation, cholesterol reduction, and a more stable microbiome.
But when oats are cooked and then cooled completely, the starch composition also changes. Several experimental studies have shown that type 3 resistant starch is formed during cooling, producing the beneficial short-chain fatty acids known as butyrate. To get the benefits, swap your hot morning oatmeal for overnight oats.
#4 Potatoes
Potatoes have some of the most significant resistant starch benefits. In a study by the University of Surrey, it was shown that fully cooled potatoes can reduce blood sugar rise immediately after eating (also called postprandial blood sugar rise) by up to 40 percent.