Harvard-trained nutritionist reveals one simple trick to cut sugar spike from carbs by half

What if you could eat rice, bread, or even mashed potatoes without causing a spike in your blood sugar? Sounds too good to be true, right? But a Harvard-trained nutritionist, Dr Terry Shintani, says you absolutely can, and with a trick so simple, you might wonder why you didn’t hear of it before. Dr Shintani, who has over 250K followers on social media, has shared a smart hack to cut the glycaemic index (GI) of common carbs by up to 50%. That means you can enjoy your carbs without the usual energy crashes or sugar rushes.

The glycaemic index is a number that tells you how fast a food raises your blood sugar. Foods with a high GI, like white bread or sweets, cause sugar levels to rise quickly. This can make you feel hungry again sooner, and over time, it may lead to health issues like type 2 diabetes or weight gain. Low-GI foods, on the other hand, release sugar slowly, giving you steady energy. Non-starchy vegetables, fruits with fibre, and whole grains are all examples of low-GI foods.

Dr Shintani’s big tip? Cook your carbs, let them cool, and then reheat them. That’s it. This process changes the starch in foods and makes it harder for your body to break it down quickly. For example, if you cook rice and let it cool in the fridge overnight before reheating it, its GI can drop from 78 to 54. That’s a huge difference. The same goes for bread, freeze it, then toast it to lower its GI by nearly 40%.

This trick doesn’t just work for rice and bread. It works for other favourites too. Dr Shintani says cooling and reheating cooked potatoes can lower their GI by 30–40%. The same process can reduce the GI of pasta by up to 50%. When carbs are cooled, some of the starch becomes what’s known as “resistant starch”, meaning it acts more like fibre. This type of starch takes longer to digest and doesn’t raise blood sugar quickly.

The next time you’re about to ditch carbs from your plate, try this instead. By simply changing how you prepare your meals, you can enjoy your favourite foods in a healthier way. This method is not only easy but could help many people who are trying to control blood sugar, manage weight, or avoid sudden energy crashes. As Dr Shintani puts it, “Try this simple hack on your carbs to keep your blood sugar in check.”