The Glycemic Index

Tom Davis

What is the glycemic index and the glycemic load?

The glycemic index of a food is a measure of how easy it is to digest the carbohydrates in that food. Pure sugar will have a very high index, since it is basically ready for metabolism with no change. If you eat a spoonful of sugar, your blood sugar and insulin will spike up within a few minutes. Foods like potatoes, dates, sugared soft drinks and so on, also have very high indices.

Foods like cauliflower, broccoli, and so on, have relatively low glycemic indices. There are carbohydrates available, of course, but the sugars and starches in those vegetables are tangled up with indigestible fiber, cellulose, and so on. If you eat these foods, your stomach needs to grind on them for a while to get out the nutrients, which will slowly enter your bloodstream. In addition to providing valuable fiber and probably more vitamins than what's in a can of Coke, since the sugar enters your bloodstream slowly, only small amounts of insulin need to be produced to perform the digestion. See the page on health benefits of the caveman diet for more information about insulin level control.

Foods can fall anywhere on a range, so the terms "high glycemic" or "low glycemic" are both relative terms. The actual numbers usually represent how quickly the carbohydrates can be absorbed compared to a food with a very high index, like pure refined sugar. If pure refined sugar is 100 and you eat a food rated at 20, that means that it is 5 times more difficult for your body to absorb the carbohydrates in that food than to absorb the pure sugar.

So the basic idea is this: when you've got a choice among different foods, generally try to choose those with lower glycemic indices.

The advice above is pretty good, but it can even be improved slightly by taking into account not only how easy it is to absorb the carbohydrates, but also how many carbohydrates there are. Parsnips, for example, have a very high glycemic index, but contain almost no sugar, so if you eat a parsnip your blood sugar isn't going to change much. Sure, all the sugar in the parsnip is very soon in your blood, but there was almost no sugar to begin with, so it won't cause any insulin spikes.

The glycemic load is obtained by multiplying the glycemic index by the amount of carbohydrates that are actually available.

A short table of glycemic indices of common foods

Rather than copy all the data here, I will simply include some pointers to pages with glycemic indices for various foods listed. You can probaby find as many such tables as you want by using your web browser to search for "glycemic index" or "glycemic load".

In any case, here are a couple of pointers to get you started:

Diabetes Mall
About Diabetes

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