OK, here's the deal:  The glycemic index is a useless number.

Now you've probably heard differently. You've heard that the glycemic index is a measure of how fast and how much food raises your blood sugar (true.) But you've also may have heard that it's a good thing on which to base your food choices (not true.) While it's absolutely true that you want to know the impact a food is going to have on your blood sugar and your insulin, the glycemic index — sad to say — doesn't tell you that.

The glycemic load, however, does.

Let's say I go into an exotic spice store and I spot an unusual spice selling for $300 a pound. Three hundred bucks a pound! You say, "That's expensive! That's a high price tag!" Well, that number — $300 per pound — is like telling you the glycemic index of a food. And while it's nice to know the "per pound" price, knowing it does not tell you how much your bill at the cash register is going to be — and that's what you really want to know! For example, even if it's 300 bucks a pound for the exotic spice, if I go and purchase ¼ teaspoon of it — which may be all I need for the dish I'm preparing — then when I hit the checkout counter, my actual bill is only 55¢!  Get it?

Point is: I want to know how much it's gonna cost me. And it's the same thing with food and blood sugar.

See, the glycemic index alone won't tell you the "cost" to your blood sugar. If you want to know what impact a food is going to have on your blood sugar (and your insulin) you have to know more than just it's glycemic index, you have to know the portion size, just like in the spice store you have to know both the absolute price ($300 per pound) and the amount you're actually going to buy! The glycemic load takes both index and portion size into account and gives you a much more meaningful number. Let me explain.

The glycemic index is a measure of how much a 50 gram portion of a carbohydrate food will raise your blood sugar compared to a fixed amount of pure sugar (glucose) or white bread. Carrots (which do have a high rating) are a perfect example of why glycemic index by itself is a useless number.

Remember our example above about the price of spices? The glycemic index is a measure of the price, but the glycemic load — a far more important measure — tells you what you're actually gonna pay when it comes time to tally up. The glycemic load takes into account how much you're actually buying, not just the price per pound. So for example, carrots, with a glycemic load of 92 seem "expensive" — but remember, that's for a 50 gram serving! There are only 3 or 4 net carb grams in one carrot! Are you likely to eat 12 of them at one sitting?

As the wonderful nutritionist and botanist at the USDA, Dr. C. Leigh Broadhurst once said, "Nobody ever became diabetic on peas and carrots."

Now sometimes a food has both a high glycemic index and a high glycemic load. That would be a good food to avoid. And some foods with a low glycemic rating actually raise insulin more than you'd guess from their rating (eggs and milk are examples, and we're not 100 percent sure why.) But by and large, the glycemic load is a good piece of info to have when you're making your food choices.
                                                
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Copyright © May 2006  Jonny Bowden and Low Carb Luxury
Photography copyright © 2006 Neil Beaty.