Glycemic Index:

The Glycemic Index is an indication of how quickly a specified amount of food will cause a rise in blood sugar level. The amount of food is the portion that contains 50 grams of carbohydrate (200 calories from carbs). So it is really an indication of how one carb compares to another.

Certain foods cause a spike, or rapid rise, in blood sugar level. This spike causes an insulin response and may over time lead to health problems such as diabetes, insulin resistance, metabolic syndrome and other issues. Maintaining a more even blood sugar level appears to be beneficial in many ways.

Only foods that contain carbs cause this spike, proteins and fats do not. They provide calories but do not cause an immediate rise in blood sugar levels. Meat and eggs contain no carbs at all, they can be considered to have a zero glycemic index. However this is not strictly true as the test cannot be carried out on them: no amount of eggs will give the required 50 gm of carbs.

The test is carried out on volunteers who have been fasting for a period of time. They are fed a portion of food containing 50 gm of carbohydrate and their blood sugar level monitored over a 2 hour period. This data is drawn on a graph and the area under the curve measured, the larger the area, the higher the glycemic index (GI). Glucose is used as the standard with a value of 100 and all other foods are compared to this.