hi notsolittlemiss and overtiredmum. i don't want to butt in but i really felt i had to post here.
i have been doing the yo-yo thing with my weight since i had my dcs (5 yrs since) and have gained over 5 stone in that time. every diet i went on, i did for a few weeks, and like you gave up at the first hint of it not working. i am just far too impatient too wait for my weight losses.
but i have recently started the cambridge diet, and although it is still very early days, i have shed 13 lbs in the first 13 days. it is a pretty radical diet in that you eat no food, only 3 shakes/soups a day and litres of water. but for me it has been a godsend as it has completely taken food out of the equation. there are no decisions to be made about what you can eat and so no guilt about what you are having. the average weightloss is a stone a month so if i do it whole heartedly, i have only 5 mths dieting rather than maybe 18 mths on a slower loss plan.
i am not trying to evangelise, and i know that this kind of regime is certainly not for everyone but it may be worth looking into. it may be all wrong for you but some people have had a lot of success with it.
there is a thread on the cambridge which i will post for you to have a peep at.
hth
xxx