I'm another Food Focus user. In April 2009 I weighed 70.5 kg (That's 11.1 stone. I'm 5 feet 2/157 cm) and had the sort of lightbulb moment that comes from a low energy bulb - the realisation slowly dawning that the problem was not any lack of clothes in the shops that I could wear; it was my denial that the 16s were tight, that I was edging towards an 18, and that OF COURSE most nice clothes were not going to look good, as I had no discernible waist.
I started to enter everything religiously onto Food Focus, jotting it down in a notebook during the day and entering it online in the evenings when I had time. I took a long and critical look at what I had believed to be my active lifestyle and made gradual changes. I bought a rebounder and started very gently in my living room. I think that my first session was about 10 minutes: that's all you need to find time for to be making a difference and starting to get more active. Do something, but make sure that it is a small change. If you declare that you are going to run a marathon straight off, or attend five classes, etc, you will feel hideous and soon feel disillusioned.
Three months later, and as I started to shrink, I started Couch to 5K.
I lost my weight incredibly slowly, which I felt to be the secret. Only one and sometimes two pounds a week; sometimes no change. I kept my eye on the bigger picture, and set myself interim goals: to be below 70kg, then to be below 10.5 stone, to have lost 5kg, etc. By the time I went on holiday that summer I was half a stone lighter, and already felt better for it. In the early days it is important to celebrate every positive development and to see where you have come from (trousers looser, a month without takeaways, the knowledge that you are heading in the right direction) is more important than looking at your final, distant destination. Never get on the scales more than once a week, and do so at the same time and day each week, naked, so that you are comparing like with like as far as is possible.
From the outset my recalibration of portion size (which had been waaaaay out), my acceptance that a "treat" is not something that you eat every day, that there is more to exercise than cycling the five minutes to walk or wheezing behind the pushchair, had to become lifestyle changes and not a "diet". This has been vital to keeping the weight off.
By the time I had finished Couch25K, I had been bitten by the running bug and wanted more.
By January 2010 I weighed 61 KG, (9 st 7) and I have now had a BMI within the normal range for a year, and this is for the first time in my adult life. I have run several 10KM races, and although I weigh myself weekly I don't get my knickers in a twist if I put on a bit: I just throttle back until I am back where I want to be. If I need further motivation I look at pictures of myself at my most lardy, and remind myself that I Freecycled all of my huge clothes.
I'm a size 12, and I'm planning to lose a bit more this spring, but nothing too much. I now love buying clothes and feel happy that I am now not going to be "the fat mum at the school gate" - a fear inside that helped me to get going in the first place.
Good luck!