What Is A Glycemic Index Diet? When you decide to follow a glycemic index diet you have to have a list of foods that you can and cannot eat. There are both high and low glycemic foods. The glycemic index is a ranking of the carbohydrates in foods that cause a marked increase in blood sugar levels after you eat them. Foods that ha... Similar Editorial : Diet Cookies by Infinitymc. | Source : Low Carb Vegan