What is Glycemic Index?

To learn more, watch this 14 minute video presentation on the Glycemic Index and Glycemic Load.

Basically, the Glycemic Index (GI) of a food represents of the rate blood sugar rises after eating that particular food. This is compared to a standard, such as glucose, which is assigned a glycemic index value of 100.

The concept of the glycemic index was first published by Dr. David Jenkins in the American Journal of Clinical Nutrition, in1981. Additional scientific publications in Europe, Canada and Australia have demonstrated the tremendous value this concept. Since the concept of glycemic index is relatively new to most people, there may be confusion about how to use it as a guide to healthy nutrition.

Generally, the higher the glycemic index, the faster the blood sugar rises in response to eating that particular food. Rapid rises in blood sugar levels can lead to overproduction of insulin, which over time, may lead to insulin resistance and the metabolic syndrome. High glycemic foods are most commonly highly processed, instant, and fast foods. Examples are white bread, white rice, breakfast cereals, instant oatmeal, refined pasta, highly processed grains, sweets, sodas, and juices. As a general principle, the more highly processed a food is, the higher its glycemic index. About 80-90% of the carbohydrates we typically eat in the United States are highly processed and high glycemic.

 

 

Low glycemic index foods are more typically whole foods, eaten in their natural state. Examples include most fruits, beans, cauliflower, brussels sprouts, oats, basmati rice, black beans, lentils, soy beans and whole wheat grains. These foods still contain natural fiber, and a healthier amylose/amylopectin starch ratio. Most raw foods have a lower glycemic index than the cooked foods of the same type.

The type and amount of specific sugars in food also have a great influence on glycemic index.

One of the most surprising aspects of the glycemic index is the wide variation in how various natural sugars are absorbed.

Fructose, the sugar found primarily in fruit, has a glycemic index of 19. Glucose has a glycemic index of 100. Table sugar, also called sucrose, (a sugar made of one molecule of glucose and one molecule of fructose), has a glycemic index of 61.

Knowledge of glycemic index helps you avoid spikes in blood sugar after a meal, and subsequent elevations in insulin levels. Glycemic index however is only one aspect of healthy eating.