This is a very interesting topic, and I think we've discussed it a bit before.
I think anyone who has been large for a long time is apt to have some issues of this sort. With the exception of a year or so at 21, again at 37 and now at 47 I've been anywhere from obese to super obese so yeah, I have some self-perception issues!
It still takes me a moment sometimes to recognize my own reflection in a mirror or store window. I'm often not recognized by people I've not seen within the last year.
I'll "never" get used to looking at smaller sized clothes--I hold up a shirt or pair of trousers and think--those are way too small--then they fit fine.
I still find myself being self-conscious in crowds, even though I'm more-or-less "normal" in appearance now.
Will this ever go away? I don't know--I'm a fat guy now inhabiting a more-or-less normal body. I think this must be how those people with face transplants feel--you KNOW who you are, and your mind is the same but your appearance just doesn't match anymore.
I think perhaps the best bet is probably just to not dwell on it.
Regards,
Michael
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47 M 5'8"
May 4, 2010...... 440? lbs. (Start FitDay Size 60 Jeans)

June 19, 2010.... 393 lbs. (First Weigh-in)
June 19, 2011.... 229 lbs. (164 lbs. gone in one year :-)
Current Weight... 185 lbs. (Size 36 Jeans)
Next Goal 169 lbs. (07/04/12)
Ultimate Goal 165 lbs. (12/31/12)
The best exercises for weight loss are Fork Putdowns and Table Pushaways.