What if Paleo/Primal married Gastric Bypass (Roux N Y) ??

Paleo/primal (I think primal is just a Mark Sisson thing) aren't inherently low carb, although I know Sisson (who I don't consider an authority on nutrition) is pro lower carb. In fact, people like Robb Wolf who have been important in writing about, popularizing, and defining the paleo diet have been talking lately about buying into low carb being a mistake that many have made in connection with paleo. I think most do reduce carbs when doing these diets since you put off limits many sources of carbs that many people rely on, but you can include any level of carbs and when I was doing crossfit more (which tends to have lots of people who do paleo-ish diets) there was always talk about how it was important to include enough carbs in your diet.

That aside (and without getting into a debate about paleo, since I personally think legumes, dairy, and whole grains can be healthy additions to a diet and even refined grains and sugar in moderation are fine), I don't know how is or a low carb plan meshes with WLS -- that's something I'd defer to a WLS medical team on.

I am post RNY and all I have to do is make sure I get my minimum protein in, which is the hardest to digest. Soft breads are hard, too. I can't see anything too difficult eating Paleo for a post-RNY patient, even though each patient will have different intolerances.

If I were trying to do both I would be most cranky giving up my Greek Yogurt and my Kefir, both excellent non-meat sources of protein.