What’s The Glycemic Index All About?

You might have heard of the glycemic index (GI) in connection with the low-carbohydrate diet — it’s sort of like that — but not entirely.

So, how would one define the glycemic index; what is it anyway? The GI is a scale that ranks foods high in carbohydrates (as opposed to fats and/or proteins) by the degree to which they can raise blood sugar levels when compared to a standard food like white bread. For example, if I were to give you a slice of white bread on an empty stomach, theoretically after an hour your blood glucose levels would rise roughly 100 per cent. If I were to give you the same amount say, of cooked lentils, the increase would only be 30 per cent. A food with a low GI would come in at 55 or less; medium would be 56 to 69; and high would be 70 or more. The glycemic load (GL), on the other hand, refers to the total glycemic response to a food or meal. One GL unit equals the glycemic effect of one gram of glucose.

There exists in various foods a range of carbohydrate and therefore the ability of a particular food to raise the level of glucose in your blood. A food that measures a glycemic load of 10 or less is said to be a low-GL food; one between 11 and 19, a medium-GL food, and 20 and up is considered a high-GL food. If you were looking at a day’s total, less than 80 would constitute a low-GL day, while a load over 120 would be a high-GL day. Still with me? OK, then how about a few examples of a GL calculation? We know (from various tables) that a half-cup of cracked wheat contains roughly 20 grams of carbohydrate and has a glycemic index of 48. If you then multiply the grams of carbohydrate by the glycemic index divided by 100, you get a glycemic load of 9.6. Another example: take a cup of carrots with eight grams of carbohydrate and a GI of 92. Do the math and you see that the cup of carrots has a glycemic load of 7.4. Those who believe that the GI is an important consideration in things dietary feel that the choice of a food rich in carbohydrate should take into account both its glycemic index and its basic composition. Not only that, the GI should be used to compare similar foods within a particular food group. Since both the amount of carbohydrate and the type of carbohydrate in a food can influence the blood glucose level, both components must be considered as well as the amount of the food that is consumed. That’s why the GI diet is thought to be superior to simply counting grams of carbohydrate — all carbs are not created equal! This is especially important for diabetics, but also of importance for those who wish to shed some extra body fat.

Breads with a low GI include pumpernickel and 100 per cent stone-ground whole wheat; at the high end would be white bread, kaiser rolls and bagels. Low-GI cereal examples are All Bran, Bran Buds with psyllium, and oat bran. Bran flakes cereals are high-GI foods as are corn flakes and Rice Krispies. In the grain department we find low-GI foods like barley, bulgur, pasta (yes, pasta — but don’t overdo it) and converted rice. Basmati rice, brown rice and couscous are medium-GI foods, while short grain white rice is high. Sweet potatoes and any of the legumes like lentils, chickpeas and kidney beans are low- GI foods, but white baking potatoes, french fries, pretzels, rice cakes and soda crackers are HIGH.

Basically you want to choose foods with a low glycemic index in order to help control blood sugar levels, regulate your appetite, to reduce the risk of heart disease and especially to lower the risk of developing Type 2 diabetes. Try and plan meals that stick to low-or medium- GI foods — but always remember that if you eat a lot of a low-GI food, your total glycemic load will still be higher than desirable.

HelenBishopMacDonaldisaconsulting nutritionistintheagriculturalindustry

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