I'm not. I've always thiigh of mysefl as a normal healthy build. In a world where a majority are over weight , I'm not that, but I don't think I'm exceptionally thin either.
I've just been for my NHS health check. A bit of a waste of time really, but I hadn't had my cholesterol checked for a while, so I went when I was invited.
I was weight and measured. 5'7", 10st1 in my clothes and 75cm waist. At both my weight and my waist the HCA explained "ooh you're tiny".