What does the glycaemic index (GI) measure?

The glycaemic index (GI) is a measure that specifically indicates how quickly carbohydrate-containing food raises blood glucose levels after consumption. It ranks foods on a scale from 0 to 100 based on their immediate effect on blood sugar relative to a reference food, usually glucose or white bread. Foods with a high GI are digested rapidly, leading to a quick spike in blood sugar levels, while those with a low GI are digested more slowly, providing a more gradual increase in blood sugar. This property is particularly important for individuals managing diabetes or those looking to control their energy levels throughout the day.

In contrast, the other options focus on different aspects of nutrition. The nutritional value of proteins is not related to the glycaemic index, as proteins affect the body differently. The amount of fat in foods is unrelated to how carbohydrates are digested and their subsequent effect on blood glucose levels. Lastly, while fiber content can influence carbohydrate digestion, it does not directly correlate with the GI measure. Fiber often slows digestion but is not what the GI quantifies; it focuses specifically on the carbohydrate’s impact on blood sugar levels.