Gosh ....ummm
The Cambridge diet is a plan where you can replace part or all of your three meals a day with food packs consisting of shakes, soups and bars.
At the 'strictest' end, it's called Sole Source (SS) because you replace all three meals and it's the sole source of your nutrition.
It works by putting your body into a mild state of ketosis ... that is, so few carbs that your body uses its own fat stores for energy.
Consequently you lose weight quickly and the averag loss is a stone per month.
Is it good? Once you've overcome the first week (pretty hard) and are in ketosis, it's quite easy because you don't experience hunger ... you do have to combat psychological hunger (I want food ... not 'I'm hungry')
As for weight gain after you stop ... if you return to the habits you had BEFORE the diet then you're likely to regain weight - but that's true of ANY diet.
I think you have to be quite desperate and very determined to go along the SS route - although there are other CD plans to suit circumstances.
How much weight would you like lose?
Hope this helps