Sounds like me, January 16th 2009. I decided I'd had enough, weighed in at 16st 10lb (think I'll always remember these stats!)
I lost 4st over a year, to be honest a 9 month period as I kind of lapsed... I started off low-Gi as I'd been advised to try, for my PCOS. The I discovered Rosemay Conley, which is also low Gi but has the benefit of exercise in the classes. I never thought I could do group exercise, or anything like that, but as it was part of the slimming club there were all sizes and ages there some a lot bigger than me so it was great. I did two classes a year but... the times changed and one class on the weeknd closed, so I had to stop going. I cheated and was crap and then lost my job and my home and moved abroad!
Anyway in December last year I kind of had that revelation again. Weighed in at 15st, not as bad as before (my highest weight ever in my life was 21st when I was 19) but still, I'm 5'2!
I started low gi, low cal, low fat then did a ton of research into the right diet for me. I started doing a VLCD which is pretty dramatic but works for me so far. Not for everyone, not even for most people. But I feel so much better on it, I've lost over 2 stone since December and I feel awake and lively all the time, and never am all bloaty and crap.
Am researching plan for when I get to goal- or close to goal- and am seriously considering low-carb. Makes so much sense to me after all these years trying on low-cal alone. I'm reading several books on the subject and I really hope it helps when I get there. I'm already low-carbing now, thats what a VLCD does but it's very different having food from packets to cooking for yourself.