In Reply to: Well, yes but also posted by Hillary on Monday, 29. January 2007 at 15:01 Bali Time:
you would weigh in at the check-in counter (discrete scales that only the check-in person can see of course). So it would record your weight at the time of check-in.
When you book your ticket you would give your approximate weight, which would be checked at check-in.
They could even have a neon 'correct weight' sign that would flash if you were in the ball park of what you'd stated when booking. :o)