I lost 4lbs on my first week on slim fast and then 1 lb per week after. I didn't exercise overly during the month I did it and lost half a stone in that month.
Then I went away with work for 3 weeks and put it all back on again and more, but when I get back from my next trip am definitely starting again but trying some of the tips from the other threads like soya/almond milk, bananas etc because the milk was starting to make me queasy.
It's great to have to not worry about the choices that you make because there is none and about portion control too but boy did I miss solid food.