"I have tried WW. SW. Pills. Veganism. Bullimia. 5:2. Atkins. Low carb. Low fat. Low calorie. I am active. I walk. I go to the gym. I am genetically lazy and greedy. I like food. I know about nutrition. I have a different excuse for every hour of the day. I have a pretty good insight into why I am fat. That doesn't stop me being fat."
Hey 
I am you. Or rather (oh god, here comes the diet bore) - I was you. I had tried everything and cried myself to sleep most nights, woken with the same 'oh christ I'm still fat and I hate myself' feeling in the pit of my (hungry) stomach, but still employed the same excuses over and over. I'm exercise-induced asthmatic. I have MS and often can't feel my legs and get tired very quickly. I haven't got time what with working and family. Eating carbs'n'shit is my only pleasure. Yada yada yada.
I eventually hit 16.11 last August, barely squeezing myself into a 22 at 5 foot 4. Not pretty, and I suspect I was heading for gastic band surgery within a year or so - I could quite easily see how out of control I was (including purging on and off for years) but couldn't do a damn thing about it.
What has worked for me is Orlistat. It's hardcore - but for me, it's the fact that when I take them, I simply can't eat carbs'n'shit - it's the simplest equation that even I, with my myriad of excuses and 'oh only one won't hurt, go on then' can't get away from. Take a tablet with 3 meals a day, don't eat crap between meals, and stay away from too much fat. I avoid things that are more than 5g fat per 100g to be on the safe side. I love the simplicity of it - if I eat what I've learned is sensibly, I lose weight. If I eat shit, I shit orange oil. It's like post-partum sneezing/bladder weakness - you really don't want to fart in public if you've been eating the wrong thing.
Pretty graphic, I know - but for me, it was just that fact that I couldn't cheat - or rather that if I did, more fool me. Of course I eat 'bad' stuff every now and again - but it's the every now and again bit that's now beginning to get under control. Every now and again is acceptable for life and won't upset my innards unduly. Eating a whole block of Caerphilly with 6 pieces of toast because I want to, goddammit, will.
If you like, I can tell you how much I've lost so far, what size I am and how I feel - but I found there was nothing worse than partly-reformed fatties telling me breezily 'oh, if I can do it, anyone can'. But... that's where I am now.
Hope this makes sense - an awful ramble and my work PC is still on Explorer v.6 so I can only see 6 words at a time...
Have a think about Orlistat - GP prescription only. I'm on a 3 month supply and get weighed at the surgery before they'll give me more. I never, ever thought I'd see myself - or that others would see me - as anything other than 'pretty face, shame about the rest of her'.