protein itself has a rating of 0 on the glycemic index, as the glycemic index only ranks carbohydrates. Feel free to add protein liberally to your meals, as long as you watch out for that pesky calorie content!
Protein is an important part of the low-GI diet because it helps slow the absorption of glucose, and hinders the rise in insulin that results from eating any form of carbohydrate.
This means that if you add some protein to a food thatís relatively high on the index, you can effectively counter that spike in insulin and glucose. By adding protein to foods that are naturally low on the GI scale, you can make an already healthy digestion process even better