Such an interesting question!
When I was 257 pounds, I wanted to be invisible. I didn't want anyone to notice me and never did anything to call attention to myself. I also didn't consider myself 'worthy' of spending time or money to look nice, so rarely bothered with makeup, didn't do my nails, never had a facial etc. And I dressed for camoflauge, not style.
When I lost the weight, I was exactly the same person who I had always been. Nothing really changed about my basic personality - my likes, dislikes, dreadful sense of humor etc - BUT I became far more willing to let my personality OUT. I didn't want to be invisible any more! Now I'm a lot more willing to be louder and more outrageous, to laugh and express my opinion - just free to be the 'me' who I've always been.
Losing weight didn't change my personality -- it liberated it.