What is glycemic index? Glycemic index is a term used to describe how quickly your body metabolizes carbohydrates. When you eat white bread, your stomach breaks it down into simple carbohydrates, or sugars. These sugars go straight into your bloodstream and circulate all over your body. Because white bread turns quickly into sugar it has a HIGH glycemic index. Whole grain bread often contains dietary fiber which slows down how quickly those sugars enter your blood, making it a LOWER glycemic index food. Low glycemic index foods help to avoid diseases like diabetes, obesity, and many more. Remember to check your labels!