Glycemic Index

By Jonny Bowden

The Glycemic Index (GI) is a measure of how much -- and how quickly -- certain foods raise your blood sugar. And the Glycemic Load is an even more accurate way to measure the same thing.

All food raises blood sugar when we eat it, but carbs raise it the most, and some carbs raise it more than other carbs. Why do we care? Because high blood sugar is not a good thing for our bodies or for our health. Our bodies respond to a high dose of sugar with a high dose of insulin -- a hormone which takes sugar out of the bloodstream and delivers it to the cells. We all need insulin, but we can have too much of it. And for many people, the mechanism that regulates blood sugar and insulin doesn't operate perfectly. Those folks can wind up with both high blood sugar and high insulin and can be at risk for a number of health conditions, like Metabolic Syndrome and Type ll Diabetes.

Even in otherwise healthy individuals, the ups and downs of blood sugar can lead to cravings, mood swings, energy dips and weight gain. Most people have experienced the "sugar rush" of a high sugar food and the nasty crash that usually follows. That's why we don't want our blood sugar to go too high too quickly. A graph of blood sugar levels in our body should look like gentle ripples on the surface of a lake, not like pounding 15 foot waves in an ocean storm.

The GI measures how quickly and how high your blood sugar rises in response to a fixed quantity (50 grams) of a carbohydrate food compared to a standard of sugar. While that's valuable information, it's also incomplete. For one thing, the GI only refers to foods eaten alone. (When was the last time you ate a meal of just peas?) Furthermore, the GI doesn't take portion size into account. Carrots, for example, have a high GI based on the 50 gram measurement, but there are only 3 to 4 grams of carbs in a carrot. The average person would have to eat an awful lot of carrots before seeing their blood sugar go through the ceiling.

That's why the Glycemic Load is a far better measure of a food's effect on your blood sugar. Glycemic Load takes both the GI and the portion size into account. Though listings for Glycemic Load are a bit harder to find than listings for GI, they're a far more accurate picture of what food really does to your blood sugar. As it becomes more widely used, the Glycemic Load will become more readily available. One good source for the load is at Mendosa.com. If the GI is all you can find, however, temper it by knowing that the numbers were based on 50 grams of carbs. So if you're eating 10 grams of carbs, the impact on your blood sugar will be a lot less.