At 13 yo, I would probably go with the books you read. What convinced you to believe Paleo-Primal was proper/right/accurate? Use those. And also - nutrition is one of those things that has to be modeled in the home to be believable to a kid. I am assuming that you are "living proof", as it were, that this WOE works, and if that is the case, you supply real-life evidence.
I have nothing specific for the 10 yo, but why not pull in that young book, anyway? I homeschool as well, and we never shy away from any book, above, at, or below grade level, if the info is accurate/appropriate for what I am teaching. One of the joys of schooling your own - everything can be used as an educational resource. If I find something, I will let you know!
I have a mantra that I have spouted for years... "If I eat right, I feel right. If I feel right, I exercise right. If I exercise right, I think right. If I think right, I eat right..." Phil-SC