The glycemic index, or GI, was developed between 1980 and 1982 by Dr. David J. Jenkins and his associates. They developed it when they were attempting to discern what would be the best foods people who have diabetes should eat.

The glycemic index measures the effect of carbohydrates on the blood sugar level.

If a carbohydrate quickly breaks down during digestion and rapidly releases glucose into the bloodstream it will be assigned a high glycemic index. If a carbohydrate slowly breaks down and gradually releases glucose into the bloodstream it will have a low GI.

Foods that have a low glycemic index usually are digested at a slower rate. They often, but not always, have lower insulin demands on the body.

Currently glucose is used as a reference food and is assigned a GI value of 100. White bread could be used as a reference food, as well. If white bread were assigned a value of 100 then glucose would have a value of 140.

What are Low G I Foods?

Low GI foods release glucose more steadily and slowly. Their GI range is 55 or less. Most vegetables, fruits, whole grains, legumes, eggs, meat, milk, fructose, and nuts are low GI foods.

What are Medium G I Foods?

Medium GI foods have a GI that falls into the 55 - 69 range. Sweet potatoes, whole wheat products, sucrose, and basmati rice fall within this range.

What are High G I Foods?

High GI foods have a GI of 70 or more. These include white bread, potatoes, most white rice, watermelon, glucose, extruded breakfast cereals, and corn flakes.

If you add vinegar to food you will lower its GI. Also, if there are soluble dietary fibers or fats present in a food they can slow down the gastric emptying rate. When that happens the GI becomes lower.

GI and Weight Control

Recent research with animals indicates that diets that are high in GI carbohydrates will increase an animal's risk of becoming obese.

One such study involved male rats. They were divided into low- and high-GI groups and subsequently were observed over a four and a half month period.

Over those 18 weeks the rats on the high GI diet ended up with 8% less lean body mass and 71% more fat than the low GI group.

In addition, post meal insulin levels, glycemia, and triglycerides were significantly higher in the high GI group.

How Can You Use the GI?

If half of your calories come from carbohydrates, you can determine which carbs you should eat and thus you can use the GI to enable you to still have lower and more stable insulin and glucose levels.

Keep in mind, though, that the amount of carbohydrates you eat have a greater impact on blood sugar levels than the GI itself. If you want to lose weight then consuming less calories and fewer carbohydrates could benefit your blood sugar level even more.

You will be able to have the most stable blood sugar level if you calculate your carbohydrate intake and eat carbohydrates with a low glycemic index.