So the closest I've come is perhaps what I would consider the "shadow" of a four pack. Let alone my past frustrations with dieting (prior to going Primal).
Its really never been my priority but I would welcome them anytime! Just looking for some ideas at what helped you get there. Is it all just a caloric deficit?
The ever ellusive "six-pack"! Most male exerciser's crown and glorY!
As you know, a defined stomach is the same as any defined muscle, low body-fat. I mean LOW. If you have 2-digit BF%, it better not be much higher that 11-12%. The 8-10% range is going to be most optimal for the display. Display also has a lot to do with actually flexing the muscles. If you don't actively flex the abs, they may not always show that "washboard" appearance. Look at the picture of Mark doing lunges w/ water cooler bottles. He is very low BF, but that picture doesn't show the "washboard".
As for how you get there, that can be a complicated answer. If you're seeing fat loss results w/ your current plan, then just keep at it until you reach a stage of homeostasis. If you're abs aren't showing after that, then you may have to play w/ CHO, macro-cycling and other "tricks" to get there.
Then again, Mark only does PB eating and has his abs in OK shape , so that says something for the PB.