People are all excited about the Paleo diet because they lose weight on it.
But the fact is, if you eat a highly restricted diet of any kind, you're probably going to lose weight. People get on the Paleo diet and become zealots, making sure that nary an iota of grain goes into their mouths. If you're paying that much attention to the food you're eating, you're probably not throwing garbage down your throat like most fat people do. So yes, you'll lose weight.
You'll also lose weight if you restrict your diet to brown rice, seaweed and overcooked lentils. Of course, you'll also lose your will to live, but that's a different discussion.
I've noticed a high correlation between people on the Paleo diet and the anti-vaccination crowd. I guess crazy is a wasting disease.
Now, you'll hear people say, "Look at all the professional athletes on the Paleo diet! They must know what they're doing." But that ignores the fact that these phony "nutritionists" hang around these athletes, trying to convince them to buy into or endorse their product/book, and if you actually look at what's on a professional team's table in training camp, you'll see a well-balanced selection from all the food groups and even a few tasty things just because they're tasty. All the Paleo stuff comes from the athletes hanging around these fraudulent "health experts" in the off-season (who also tend to be the ones to get them to use performance enhancing drugs like deer antlers and human growth hormone). The guy in Florida who is facing serious federal time for running a PED-ring got started in the business with a product called (I'm not making this up) "Zap Your Zits With Zinc" where people paid outlandish sums for less than a penny's worth of zinc (which also happened to be a near-toxic dose, if I understand correctly). It didn't clear up anybody's skin, but it got the "nutritionist" started on the road to making big money giving guys in the gym stuff to make them all swole up like mesomorphic bratwursts.
Now, there are certain aspects of the Paleo diet that appeal to me, like the fact that you can eat all the spare ribs you want, the fattier the better. However, I don't see how any diet that rules out italian bread with fresh mozzarella and olive oil washed down by cold beer could possibly be good for you.