The glycemic index (GI) is a rating system for carbohydrates that indicates how quickly these foods raise blood sugar levels. Glycemic response ratings range from 0 to more than 100, with pure glucose rated at 100 for comparison. Foods with higher ratings cause the fastest rise in blood sugar.
Function
The GI identifies foods that have the greatest impact on blood sugar so that anyone who has a problem balancing blood sugar, including people with diabetes, can avoid these foods.
Significance
Foods with a high GI rating provide more immediate energy but may cause health problems, while foods with a low GI rating help you feel fuller faster and stay satisfied longer and may help you eat less overall.
Levels
A GI rating of 70 or above is considered high; foods with a high GI include white bread, doughnuts and jellybeans. A GI of 55 or less is considered low; low-GI foods include nuts, whole grains and dried beans.
Types
Sugary, low-fiber foods generally have a high GI and healthier, and high-fiber foods tend to to have a low GI, but there are exceptions. For instance, a baked potato has the same GI as a doughnut.
Considerations
The GI measures each food as it is eaten individually. When foods are eaten in combinations, as in a normal meal, the GI changes for each food and the overall balance of the meal becomes more significant.
