As discussed throughout, the glycemic index (GI) is a dietary measurement system which allows for determining how quickly the blood sugar rises after consuming a carbohydrate-rich food. The higher the glycemic index value of a food, the more quickly the food (carbohydrate) gets broken down in the body and the faster the rise in blood sugar.
Limitations with the Glycemic Index and Weight Loss
Although useful, the glycemic index is not a perfect foundation for a weight loss diet, no matter how valuable it is for determining food-conversion into blood sugar.
The Glycemic Index does not count calories
The main drawback with glycemic index diet theories is that the glycemic index does not take into account total calories for a meal. The overall most important factor in determining a healthy diet is to maintain a balance between calories in and calories used for energy.
The Glycemic Index does not change with portion size
The glycemic index of a food is not influenced by the portion size. So if a person diets with spaghetti (43), because it has a lower glycemic index than baked potatoes (93) - and consumed large quantities of it, the person would gain weight.
The Glycemic Index does not correlate with multiple food combinations
The glycemic index only ranks single-foods. So it's not a very accurate guide to the changes of blood-sugar that may occur with a meal.