I have tried the 48 hour diet-not for weight loss, because I am an exerciser and calorie counter, but for detoxifying my digestive system. It works great if you can stick with it for the whole 48 hours without eating anything else. You will lose a few pounds, but it is mostly water weight and the cleaning out of your digestive tract.
If you want to do the same thing, only cheaper-I recommend 1-2 days of nothing but fruit and vegetable juices-just make sure they are 100% juice. V-8 and fruit juices such as grapefruit and pineapple are the best.
Just make sure not to work out too hard or do a lot of strenious activity. Drink a lot of water as well, especially good if mixed with a touch of lemon.
Hope this helps!