Every morning I have a breakfast smoothie made with one scoop of whey powder, berries, honey, green tea, and a little coconut milk (plus two eggs). They whey powder is most of my 15%, chocolate is the other 5%. It works for me. I "eat real food" for lunch and dinner and don't have time to whip up a steak every morning.
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.