What does the glycemic index measure?

The glycemic index specifically measures how quickly carbohydrates in a food raise blood sugar levels after consumption. It provides a ranking of carbohydrate-containing foods according to their effect on blood glucose. Foods that score high on the glycemic index are those that cause more rapid spikes in blood sugar, while those with a lower score result in a slower, more gradual increase. This measurement is particularly important for individuals, such as those with diabetes, who need to manage their blood sugar levels effectively.

The other options relate to different nutritional components but do not pertain to the glycemic index. For instance, the content of protein, calories, or fiber in food does not determine how the food affects blood glucose levels. Instead, those measurements assess other nutritional aspects, such as overall energy, macronutrient balance, and dietary fiber, which are not directly related to the glycemic response in the body.