Hi thatch!
I seem to be your twin... i m 5'3 and started out at 12.7 2 weeks ago,i lost 5lbs the first week and think i ve lost 2/3 lbs dont really weigh myself until a monday.I only have a slim fast shake in the morning or if i m in a hurry or on the go i'll have a slim fast bar.Then i will have normal lunch but not over 250 cals and then dinner 600 cals and maybe fruit and fat free yoghurts in between. every second day i'll treat myself to a small packet of buttons and suck them for ages to get my chocolate craving to disappear,then i wont go binge eating!!
Then from about 7pm onwards i'll drink 2 ltrs water(avoid doing in day time as you run to the loo every 10 mins) and do 10 mins resistence bands on my upper body( these together have really toned my arms,back and shoulders).Thats it really,if i can squeeze it in i'll do half hour to hour of fast walking too.But everybody is different and loses more or less depending on how much they retain.If you had 2 slimfast shakes and stuck to their snacks etc. i'm sure you would loose alot in the first week.??
One girl on another thread lost 10lbs in her first week!!
Give it a go for 2 weeks and if you then decide it's not for you then choose another plan that is.
Best of luck!
Let me know how you get on....