At a recent Cognitive Behavioural Therapy workshop, this kind of thinking was called a "core belief" and I think that's true. I remember my mom and even my grandma, from the time I was little, having the same struggle and giving me the message over and over, "You'll gain weight as you get older. You won't be able to stay skinny. Dieting is hard." So I guess I come by this core belief honestly.
Evidence, too, supports this belief, as I've never been able to maintain the weight that I want to be at. Every time I lose, I regain. I think that this is the hardest belief to combat and is a big part of my current resistance to even trying.
I feel a great deal of compassion for this part of myself, though. Because along with this core belief is it's companion - "No matter how successful you are, you'll never really be good enough."
Part of me wants to come up with antidotes and alternatives to this core belief right away, but that would be a way of pushing it aside and pretending that it's not there. Instead I think that for now I'm going to sit with this belief, to watch it as it plays out in my day to day life and see how it influences me. By getting curious, I'm hoping to shine some light on the "monster in the closet" and hopefully will find a way to deal with it.