Understanding Glycemic Index
Glycemic Index is not easy to understand and several points need to be emphasized:
1. GI is non-intuitive: Nobody can predict the exact GI of a food without measuring it.
2. GI can change dramatically by adding other foods
3. Generally, adding low-glycemic or non-glycemic foods to high GI foods will LOWER and not raise the overall GI of a meal.
4. GI is only useful for foods that contain absorbable carbohydrate. This means the GI is not measured for "non-glycemic" foods like pure meat, eggs, fat or pure fiber.
5. GI can only be determined through measurement of blood sugar level in ten human volunteers over many weeks.
6. Because of this, it is very labor-intensive and expensive to measure the GI of foods.
7. Because of the work and high cost involved in measuring the GI of foods, only about 4000 foods have actually had their glycemic indices measured. In other words, we don't know the GIs of many foods.
8. It is easier to predict a low-GI food than a high-GI food. To put it another way, nearly all foods with dilute carbohydrate that is mixed with lots of fiber, protein or fat will have a relatively low GI, BUT, not ALL foods that are nearly pure carbohydrate will necessarily have a high GI. This means that generally, you're safe eating whole grains, whole vegetables and fruits (except watermelon which is high-GI). Also remember that foods with very little carbohydrate like meats have almost no effect on blood sugar.