I never use Whey Protein as a meal, only as a supplement for my macros. Whey Protein in bulk is cheaper than buying a bunch of meat, and lower in calories too (A 33g scoop of my Whey is 25g of protien and 130 calories mixed with water). Of course I still eat regularly but only use the Whey to hit my target protein goal on workout days (which is known popularly to either by .8 or 1.0 gram of protein per pound of body weight).