I have a scoop of whey powder (18 g protein) in my breakfast smoothie. The "real food" police don't like it, but I tell 'em it's my 20% and they can go pound Himalayan salt. IMO it's a good way to get complete protein without eating steak for breakfast.
5'0" female, 44 years old. Started Primal October 31, 2011, at a skinny fat 111.5 lbs. Low weight: 99.5 lb on a fast. Gained back to 115(!) on SAD chocolate, potato chips, and stress. Currently keeping food tracker.
I (try to) follow by-the-book primal as advocated by Mark Sisson, except for whey powder and a bit of cream. I advocate a two-month strict adjustment for newbies. But everybody is different and should tweak Primal to their own needs.