What is The Glycemic Index (GI)?
Knowledge is power. So here's a quick guide to what the glycemic index is, and why it matters.
The glycemic index (GI) ranks food rich in carbohydrates by how quickly they are broken down into sugar by the body.
The higher the GI rating of a food (glucose has a GI score of 100), the quicker it is broken down into sugar, and the faster blood sugar and insulin levels will rise.
Foods with a high GI (70+) include white bread, potatoes, cakes, doughnuts, croissants, bagels and a lot of breakfast cereals. Moderate glycemic index foods (56-69) include corn, white rice, and coucous, while low glycemic index foods (55 and below) include most fruits and vegetables, beans, wholegrains, low-fat dairy foods, and nuts. Pasta, despite being a refined carb, also has a low GI.
It’s a mistake to think all high GI foods are bad for you, however. Watermelon has a GI score of 72 whereas table sugar (sucrose) has a GI of 59. That said, you can see instantly that some of the foods we know are not good for our weight or well-being have high GIs, and it’s never a bad idea to swap them for lower GI versions: choose wholemeal bread instead of white bread, brown rice instead of white, maybe pasta instead of potatoes.
You can also lower the GI of a meal by serving carbs with fat or protein, both of which slow down the absorption of carbohydrate. How you cook food can also affect its GI value. A boiled or roasted potato typically has a GI of 59 or more, while a baked potato has a higher GI (69) and mashed potato a higher still GI (78).
A 2005 study by scientists at Lund University, Sweden, found that if you take that boiled potato, put it in the fridge for 24 hours and then serve it cold, you’ll lower its GI. Serve it with a simple vinaigrette (vinegar and olive oil) and you’ll lower it even more. The reason for this is that cold cooked potato contains more fibre-like resistant starch than freshly cooked hot potato and so less sugar finds its way into the blood stream. A 1987 study published in The American Journal of Clinical Nutrition found that 97% of the starch from a freshly cooked potato was absorbed during digestion compared to only 88% of the starch from a cooked and cooled potato.
Potato salad anyone?
INTEL In Italian restaurants, and of course in Italy itself, pasta is typically served al dente, cooked to be firm to the bite. Cooking pasta for a shorter period (three to six minutes, typically, depending on the pasta) not only improves the taste and mouth feel, but also results in pasta with a lower GI than pasta boiled to within an inch of its life. All pasta doesn’t taste the same either. Try a brand like De Cecco, cook it al dente, and the extra pennies spent will be rewarded with a better taste and better health.
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Article last updated: 24th January 2021
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