HOW do I stop self-sabotage?

I am in self-coaching scholars, and am reading y our “If I’m So Smart, Why Can’t I Lose Weight” book now. I read that belief systems and reality like to match, and if I maybe unconsciously do not believe I can lose weight, that I may be self-sabotaging my efforts to lose weight by eating more on a day I had previously decided I would begin doing all the right things, because of this unconscious belief that I can’t lose weight. I have been told I can’t. My thyroid is low. I am 50 and peri-menopause might make it harder. I have lipodemia. I am told over and over again that I won’t/can’t lose weight. Should I believe that? How can I change my belief system about that so I don’t sabotage my efforts? Once I was very slim. Then I gained 80 lbs in one year. I cannot stand it. What do I do?