well it depends on what you are trying to do. there are a ton of different protein mixtures out there. some are more for cuttin with low carbs, little to no fat, and not super high amounts of protein. these generally mix with water. there are builder protein mixtures which always give the nutritional facts with water, and with 2% milk. I mix mine with milk since im normally on test and eq, plus i just dont tend to add a lot of bad weight. and usually with the 2% u get a couple hundred extra calories over water, higher carbs and protein. thats my 2 cents bro...