Glycemic index refers to a food’s ability to raise blood sugar to a particular level within a given period of time. Glycemic index applies only to carbohydrate foods because they are the foods that most affect blood sugar levels.

Some starchy foods have a high glycemic index. These foods may cause high blood sugar levels after meals. High glycemic foods include instant rice, baked potatoes, and raisins. Foods that contain mostly fat and protein do not affect blood sugar levels very much, so their glycemic index is not calculated.

Most nonstarchy vegetables, fruits, and legumes have a low glycemic index. These foods may help prevent high blood sugar after meals. Low glycemic foods include rye grain, dried beans and lentils, apricots, and peanuts.

The glycemic index of a food can change depending on the variety of the food (for example, red potato or white potato), its ripeness, how it is prepared (for example, juiced, mashed, or ground), how it is cooked, how long it is stored, and the foods eaten with it.