Fat wasn't my demon. Sugar was and fat was just the side effect of too much sugar. I'm not fat (and haven't been since my late teens) but I know my body and mind well enough now to understand it's "unhappiness" or "anxiety" triggers.
I eat emotionally and here's my story. A while back my mum had a serious health scare so I self medicated with a bottle of wine each night, bags of haribo and blocks of chocolate for about a month. But sugar feeds sugar and the only way I can stop the cravings is to cut it all out.
So I went no booze, no sugar, no processed foods, no dairy, no grain. Just healthy fats, protein and a shit ton of vegetables (and minimal fruit for the first 2 weeks because sugar is sugar). And once I started eating like this and the sugar cravings stopped after a few days, it felt good to put good stuff in my body, which made me want to pick up my exercise levels because I had more energy and so on.
I don't miss sugar, or cake, or ice cream or chocolate, or most importantly, alcohol. Because I don't eat sugar I don't crave it any longer.
This demon is an external influence not an internal one. It doesn't reside inside me, the sugar demon doesn't belong to me, it was something I was putting inside of me that was causing the weight gain and the lethargy and the cravings and the lack of will power and I just didn't realize that until I cut that bastard off, I'm going to keep going around in circles.
Being fat is not your demon, it is a by product of something you're putting in your body that is causing you to comfort eat or overeat.
I can't recommend cutting out sugar more highly, it has given me a clarity and lease in life that I never thought possible.