What is the glycaemic index (GI) used to measure?

The glycaemic index (GI) is specifically designed to measure the impact of carbohydrates in food on blood-glucose levels. Foods with a high GI are rapidly digested and absorbed, leading to a swift increase in blood glucose levels, whereas those with a low GI result in a slower, more gradual rise in blood glucose. This is important for managing energy levels, weight control, and for individuals with diabetes who need to regulate their blood sugar levels.

In contrast, the other options address different aspects of nutritional content that are not related to the glycaemic index. For example, fat content pertains to the amount of fat in food, protein quality refers to the amino acid profile and digestibility of protein sources, and caloric density measures the number of calories in a given weight of food. None of these metrics evaluate how carbohydrates affect blood-glucose levels, distinguishing the GI as a unique and essential measurement for understanding the body's response to carbohydrate intake.