What does the glycemic index measure?

The glycemic index specifically measures how carbohydrate-containing foods affect blood sugar levels after they are consumed. It ranks foods based on how quickly and how much they raise blood glucose levels compared to a standard reference food, usually pure glucose or white bread. Foods with a high glycemic index cause a rapid spike in blood sugar, while those with a low glycemic index result in a more gradual increase. This measurement is particularly useful for managing conditions like diabetes, as it helps individuals make informed choices about carbohydrate intake.

In contrast, evaluating the effect of fiber on digestion relates to the role of fiber in the digestive process and its ability to slow absorption, which is not the focus of the glycemic index. The nutritional value of proteins pertains to their amino acid content and contributions to muscle and overall health, while the caloric content of food speaks to the energy provided by food items, neither of which directly relate to how carbohydrates influence blood sugar levels.