There's a lot of bacteria in your gut - it contains something like ten times as many bacterial cells as there are human body cells in the whole of your body. They're a lot smaller, of course, which is why you don't actually weight the best part of a tonne, but it still makes a measurable part of your body weight.
After 48 hours, I'd dropped at least 5 pounds weight.
I've now put a couple of pounds back on, some of which will be fluid replacement. But oh, I really don't recommend it as a weight loss treatment.
As of Saturday, I should be safe to visit a hospital.