milk digests slowly i think... so that'll probably affect the absorption time of the protein in ur shake... thats just wut i think tho
Milk digestion is not that slow.... The GI is low because the rise in glucose occurs slowly due to 50% of the carbohydrates being galactose - which means it requires conversion to glucose in the liver before it will effect blood glucose. So you still get the other 50% glucose in your blood quickly. However, due to the unique combination of the carbohydrates and BCAAs present in milk, it is highly insulinogenic - so you still get a high insulin response.
The casein protein fraction is slower to digest, and it generally seperates out in the stomach, but the liquid fraction of the milk (whey, carbs, electrolytes and water) will continue to be digested without much delay.