Solid foods all take different times to digest depending on what the food is and how its cooked or not. How long does it take to digest a protein shake? Lets say 40 grams of protein and 10 grams of carbs.....
Time from ingestion to presence in blood: 1) Free Form Aminos (Pharmaceutical grade)- 60 minutes 2) Hydrolyzed Whey Protein (Peptide Level)- 80 minutes 3) WPI- 2-3hrs depending on quality and processing 4) Micellar Casein- Steady delivery 3-6hrs 5) WPC- Indeterminate variability in quality, processing and actual protein content is too high
According to George Farah, who is one of the best dieticians for bodybuilders, about 20 min. He recommends protein shake wait 20 min then take in your carbs. This maximizes your Growth Hormone levels. He talks about it on youtube at a seminar he did with Kai Greene
read some studies a while back done by optimum nutrition that said as a general rule, the body can effectively and fully utilize 60 grams of protein in a single sitting and that 4 hours is the optimum time between consumptions.
it is also why ON limited their servings to 60 grams are thereabouts. but the pro complex powder I use by them is a mixture of proteins. each included for its own merits and I believe they use both fast and slow absorption types.