Had a shake yesterday after my workout and a rather well respected person at my gym told me that I should never have my shakes with skim milk. I was told that it slows down the digestion too much being that the shake was made with skim milk. I don't see how that should effect the digestion because it is low in fat. However I did some research and found that milk is around 80% casein which does slow digestion significantly. Does it really matter how fast the protein is digested or not?