The human body has a design mechanism so if there was a famine your body would store excess fat to use (just like a camel has the humps on its back to live off when there is no food). By eating regularly and eating enough your body realises there isn't a famine and thus doesn't cling onto any fat. But if you don't eat enough your body goes into "starvation mode" and thinks there is a famine ahead and hangs onto the fat.
So with WW you must eat all your points, whatever your allowance is. Have a potato with that meat salad, or eggs with your breakfast ...... ooooh, the list of tasty food is endless.