The Glycemic Index measures the effects of the Carbohydrates in a given food on blood sugar levels. It estimates how much each gram of available carbohydrate
(total carbohydrate minus fiber) in a food raises a person's blood
glucose level following consumption of the food, relative to consumption
of glucose. Glucose has a glycemic index of 100, by definition, and other foods have a lower glycemic index. Glycemic index is defined for each type of food, independent of the amount of food consumed. Glycemic Load accounts for the amount of food consumed and is calculated in terms of glycemic index.
Followers of an Ancestral ~ Paleo ~ Primal Diet should be aware of these numbers to avoid excess sugar/glucose intake and the respective surge in Insulin to clear it from the bloodstream. Eating the right (low glycemic) vegetables becomes second nature after a while
and a quick glance at a few of these charts on the links below will be useful to make good decisions. Combining and ensuring that your meals contain protein and fat, in addition to the carbohydrate selection, affects the Physiological actions for the better that happen in response to the total glycemic load of the meal.
Grains, Beans, and refined sugars, as you already know, are a no-no,and upon looking at most of their GI's, it should have you convinced.
Glycemic Index Links: