I just wanted to weigh in on your comment here because I think this is a huge misconception. The paleo / primal diet is really not a "diet" per se. A diet is a short term solution to a long term problem.
Short term, long term, diet, lifestyle, doesn't matter. The hunter-gatherers on whom the so-called "paleo" diet is ostensibly modeled lived in conditions of food scarcity and had to do hard physical labor for what they could get. If you hope to mimic what they ate (which you really can't, but never mind that), based on the idea that it was somehow healthy for them, you also need to eat the same quantities and live the same kind of life. And then die at 40.