I am the same way too, and I think it has to do with childhood experiences. I came from a very dysfunctional family where there was only criticism and insults. There was no nurturing at all. Both my parents worked and we always had babysitters. I think we internalize things that were said to us as children and then we verbally abuse ourselves. Because I never felt loved and accepted as a child I grew to hate myself--everything about myself and still do today. I think you have to listen to an audiotape of self affirmations. I was reading some info about reprogramming the subconscious mind. YOu have to substiute the negative thoughts with positive ones.
I hope this helps a little.