I saw this on another forum
You want a STEADY influx of amino acids, not a big dump of them and nothing. A piece of steak or chicken is leaching out amino's into your blood for 8-14+ hours. Casein 6-7, whey, 1-2. Do you REALLY think you are synthesizing that much muscle tissue in 1-2 hours. Because that is what you are trying to do with whey. It is very insulingenic also.
THAT is the short answer--believe what you will, but whey is a CRAP protein for anything except PWO, OR, to add to a WHOLE FOOD MEAL. As a meal replacement the way most people use them, it just leads to an epic failure for most lifters.