Don’t worry I was the same, I am also classed as ‘underweight’ but I feel perfectly healthy and fine, I think it was quite rude of the nurse to ask if you had an eating disorder! Some people might be seriously offended by that.
At my pre-op the nurse also took my blood because of me being underweight but the blood test came back fine.
Mya contacted my GP to see if there was any reason why I’m underweight and I was worrying so much that I might not be able to have my surgery because of this but believe me it’s totally fine. I had my operation on Saturday and everything went fine, the fact that I’m underweight didn’t affect the anaesthesia.
Good luck you’ll be fine ? xx