Pah. If it reduced my cost, I'd lie too. And I'm not overweight at 70kg. If saying I'm 60kg saves me a few moneybucks, why wouldn't I. A weigh in would work better, but would make the whole flying process even longer. Can you imagine suffering through that long check in with every single passenger trying to bargain with the airport personel about the reading on the scale? Sounds like a special level of hell.