The Glycemic Index (GI) is a system that ranks foods on a scale from 1 to 100 based on their effect on blood sugar levels. Some foods make your blood sugar rise very quickly because carbohydrates like refined sugars and bread are easier for your body to change into glucose. Carbohydrates like vegetables and whole grains are digested slower requiring less insulin to metabolize them.
Your body performs best when your blood sugar is kept level. If it drops too low, you become tired and crave sweets. If it goes too high, you have to produce more insulin to bring it back down but it converts the excess sugar into fat. Therefore, when you eat foods that cause a large and rapid glycemic response, you may feel an initial elevation in energy and mood as your blood sugar rises, but this is followed by a cycle of increased fat storage, lethargy, and more hunger! Increasing fat storage may sound bad enough but people with diabetes (type I & II) have an even worse problem. Their body’s inability to secrete or process insulin causes their blood sugar to raise too high, leading to a host of additional medical problems.
The theory behind the Glycemic Index is simply to minimize insulin-related problems and weight gain by identifying and avoiding foods that have the greatest effect on your blood sugar. You can get the list of the Glycemic Index of foods on line which is important because it is surprising to see. For example sweet and sugary foods are definitely high on the GI list however some starchy foods like potatoes or white bread score even higher than honey or table sugar!