Here's an interesting piece from wired on how weightwatchers is essentially a roll playing game that pretty much drops the programs docs.
"When you first log in to Weight Watchers, it determines how much food you'll be allowed to eat that day, expressed as a number of "points." My friend gets 23 points per day."
"But pretty soon she learned to hack her daily eating to suit the system. She snacked on vegetables that took zero points -- like bell peppers -- or only one or two points, like a tasty brand of microwave popcorn. Then she'd save up the big points for a really decent dinner. Better yet, Weight Watchers assigns her an extra 35 bonus points per week that she can use if she goes over her daily limit. Or she can bank them for a big blowout restaurant meal on the weekend."
Here's a nifty free (though not as extensive) version of their online calculator.
Here are some manically happy and perky people: