Just to add to what Leanne has said, I did get weighed (althought not measured). This was because I had banished scales from my bathroom for a long while in fear of what I might find, and therefore had no idea what I weighed.
Conversely I have known for many years that I am exactly 157 centimetres. Don't ask me how I came by that particular piece of mostly useless information though, becuase the reaosn is lost in the midsts of time.
In short, if you know your weight and height, they probably won't take them.