I agree really, I think that when you do that, you're not really learning anything about how to change the habits that got you to put that stone on in the first place, so it's hard to keep it off.
Also, this is the calorie counting section, there is a VLCD section as well. Unless you mean that you're going to do it yourself, instead of using something like Lighter Life or Cambridge Diet in which case, I'm sorry but I can't wish you luck as you're doing something that's actually very bad for your body. VLCDs like Lighter Life have got doctors and nutritionists behind the scenes carefully planning out the shakes, bars, soups etc so that each one is nutritionally balanced so that even though you have very low calories, you're still getting all the nutrients that you need. If you're going to do that yourself then you won't be getting those nutrients, it's impossible to. Even eating 1200-1400 a day I make sure that I take multivitamins because of that. DIY VLCDs are not good for you in any way, yes you lose the weight, but you'll be losing muscle as well as fat, which will lower your BMR and make it even easier to put the weight back on after. A VLCD should ALWAYS be a supervised and medically planned programme, never just something that someone plans out themselves. I know that it's only a week but quick fixes don't work, ever. You'll lose the weight, keep it off for a couple of weeks maybe and then put it back on, probably with at least a few extra lbs because of your decreased muscle mass and sending your body into starvation mode. If you really want to lose that weight then there are plenty of people here who can help you to lose it in a healthy way and yes, it will take a little longer, but it's better in the long term for your health and also your chances of keeping it off.