Consider the typical American diet and what they snack on and compare it to eating nuts; I'd be amazed if it didn't tend to make it more difficult for those people to get the same amount of calories. I wonder if you've had the kinds of nuts paleo dieters eat. They're unsalted and uncooked walnuts, almonds, or pecans (typically almonds) -- not exactly a superstimulus.
And remember, you need 24 almonds to get ~128 calories.
You're right, I was imagining peanuts, which are probably much worse.
I recently came out against paleo in the open thread, and realized that I probably haven't yet heard the strongest arguments in favor of a paleo diet. So, what are said arguments?
EDIT: Or more generally, why should I eat less carbohydrates and more protein / fat?