The Glycemic Index and Glycemic Load Theory

In 1981 researchers David Jenkins and Thomas Wolever of the University of Toronto published a study suggesting that the "glycemic index" of foods be used to classify carbohydrates rather than the traditional "simple" and "complex" system.

Contrary to traditional belief, the study found that complex carbohydrates were actually digested faster than simple carbohydrates. Therefore, complex carbohydrates increased blood sugar much faster than simple carbohydrates.

Glycemic Index

Glycemic index (or GI) is a ranking of how fast a given food triggers a rise in blood sugar level. The developers of the glycemic index used pure glucose as the standard, giving it a rating of 100. Therefore, the closer a particular food is to 100, the higher its glycemic index.

All foods that are ranked by GI are based on 50 grams of carbohydrates, regardless of how much of that food it takes to reach 50 grams.

High	GI of 70+
Moderate	GI of 56 - 69
Low	GI of 55 or less

When high GI foods are consumed, the pancreas detects that rapid rise and quickly pumps out a high level of insulin to balance the blood sugar levels. The result is a sudden "crash" in blood sugar. This sudden "crash" of blood sugar level is thought to create cravings for more carbohydrates, resulting in a vicious cycle of abrupt ups and downs and over eating. Low GI foods are digested slower, therefore there is a gradual rise and descent of blood sugar when insulin is released from the pancreas lessening carbohydrate cravings.

Glycemic Load

Although the glycemic index ranks how rapidly a particular food turns into sugar, the serving amount is not clear. The glycemic load is a ranking of how much a standard serving of food raises your blood sugar. The lower the glycemic load, the less a serving of food will trigger your blood sugar to spike.

High	GL of 20+
Moderate	GL of 11-19
Low	GL of 10 or less

The glycemic load of a particular food is calculated by multiplying the amount of carbohydrate in a serving by the glycemic index and dividing that number by 100. For example:

1 serving contains 12 grams of carbohydrate (carbs less fiber)

Food item has a GI of 40

The glycemic load of the food is: 12 X 40 / 100 = 4.8 (rounded to 5)

This food has both a low GI and a low GL

1 serving contains 56 grams of carbohydrate (carbs less fiber)

Food item has a GI of 45

The glycemic load of the food is 56 X 45 / 100 = 25.2 (rounded to 25)

Although this food item has a low GI of 45, the GL is high at 25, an indication that you should be careful with portion size and how frequently you eat this food item.

The examples above help to explain why the glycemic load (GL) value of a food is a better tool than the glycemic index (GI) value of a food when evaluating the foods you eat.

Factors That Alter Glycemic Value

Cooking process
The amount of processing the food has undergone
Amount of fiber present in the food
The addition of fat/oil to food will lower values
The addition of acid (such as lemon juice) will lower values
The addition of vinegar will lower values

All of the above factors have the ability to alter the glycemic effects of food.

When eating high GI or high GL foods, adding fat will slow down the rise in blood sugar levels, i.e.: add peanut butter to a slice of bread.

High insulin levels are also believed to play a part in diseases such as diabetes, high cholesterol, blocked coronary arteries, high blood pressure, strokes, and obesity. Controlling spikes in insulin may help to alleviate some of these health risks.

The Glycemic Index and Glycemic Load Theory

The Glycemic Index and Glycemic Load Theory Reviews