As Lyn says above a VLCD like cambridge will see you lose about a stone a month but i struggle with the not eating food thing - some people do it very successfully.
I've chosen Go Lower because it puts me in ketosis like a VLCD diet but you eat real food and more calories. The company delivers the food to your door and you just stick it in the microwave (sounds disgusting but the quality of the food is very high)
As Lyn says it's not cheap (£200- £250 a month) which is about the same as lighter life but more expensive than Cambridge but I've decided my health is worth that little extra bit and actually when i added up how much I spent on weekly groceries, snacks, eating out, starbucks, takeaways etc it's about what i was spending anyway.
You don't go to classes and have weekly weigh ins but theres a support line that you can call at any time and they are really helpful (eg I went out to dinner a couple of weeks ago and was able to send them the menu so they could suggest which would be the best food options)
As Lyn says the place to start is to decide 1) do you feel strong enough to do it yourself or do you need weekly weigh ins/ class support 2) do you want to lose it in the fastest possible way by cutting out food or would you rather eat food 3) if you want to eat food do you want to be able to eat anything just in a more controlled way (eg something like weight watchers points) or would you rather have a plan where you can eat some things and not others 4) do you want to cook and prepare the food yourself or have it delivered (there are quite a few food delivery services avaiable at the moment - go lower is just one of them).
Having looked at all the q's above I decided Go Lower was the right plan for me (unfortunately as you point out because it's not well known it took me a long time to find it but know I have I found "my" answer) - just had a weekly weigh in and have lost 11lb in 4 weeks - my suggestion would be to look at all the different options and decide which one is right for you - and any questions you've got before you start or once you've started there will always be someone on here to help you out.