I can just offer my opinion. I read The Primal Blueprint and lots of the great information on this site. By following the Primal Blueprint dietary rules, I lose fat. When I start flaunting the rules, I gain. So my answer would be, if you haven't already, read Primal Blueprint (or the dietary information on this site).
I find it hard to dispute the facts and figures that Mark back's up his dietary suggestions with. But I also buy into the whole PB lifestyle program.
Does that mean you'd have to follow PB to lose fat? No way. Years ago I lost a significant amount of fat on the Body for Life Program, I was eating lots of non Primal stuff. I was also doing chronic cardiac, and other non PB things. For me, personally, I like the PB approach better, and I'm sticking with it.