I just finished reading "Why We Get Fat" (http://www.amazon.com/Why-We-Get-Fat.../dp/0307272702
). It was fascinating look at the subject from all sorts of points of view, very scientifically oriented. The short answer is the same one reached by Atkins, South Beach, etc. Our bodies aren't designed to run on the amount of sugar and carbohydrates we fill them with. Both spike our insulin and make our fat cells go nuts. Fat is a function of what your body does to the food that you put it in. Certain kinds of foods get treated differently. And once your body chemistry gets out of whack, your food cravings adjust to maintain it. You aren't fat because you're eating "too much"; you're eating too much because your fat. Counting calories doesn't it get it done because fat isn't a function of energy regulation.
What I love about the approach the book recommends is that its just so logical. If you're on a diet that leaves you hungry, your body is telling you that you aren't doing it right. If eating leaves you lethargic instead of energized, you aren't doing it right. Basically don't worry about how much you're eating, worry about eating stuff your body doesn't need.
I've cut out sugar almost completely and drastically lowered carbs and I'm down from 245 to 220 over the last 6 months. What's crazy to me is how much you notice the change in sensitivities. If I have a big meal of pasta now, I can feel my body react. Things that previously didn't taste particularly sweet are now quite sweet, like milk. Overall I just feel so much better and I'll never have to stop "dieting".