I do that all the time. Its wonderful to know that I am not the only one thinking that when I am out. I find myself looking at others and comparing. I even ask my husband if I am skinnier than that girl, or this girl...
I know that my perception of myself is entirely different than all actuality, but when he tells me she is skinnier...or something that I don't want to hear it just makes my condition worse.
One thing that is hard to see is others who you know are anorexic, or are struggling with another ED. I heard a girl in the bathroom at the movies a while back perging. All I wanted to do was to talk to her and tell her she wasn't alone and ask if she was getting help...but I couldn't.
Just some thoughts added to yours..
Novblis