In the last 4 weeks (28 days actually) I've dropped about 7% bodyfat.
Granted I started out rather high -- just over 20%. I'm currently sitting at about 13.5%. At my bodyweight of 205, that's about 14 lbs of fat loss.
I'd doing a CKD, with a 36 hour carb-up every week. Keep in mind, I've done this diet before with A LOT of tiral and error, and now I'm at the point where I know exactly what I have to do in terms of lifting, cardio, diet, supplements, etc.
So my answer is that total fatloss would depend on where you're starting at. If your already fairly lean (like 12% or so) don't expect to get cut up in a month. But if you're a chubby fucker like I was, I don't think it's out of line to expect a radical drop in bodyfat within four weeks.
Of course, steriods and thermos are X factors. I'm sure with some juice and T3 you could lose a lot more fat. I don't know much about that route, so I won't comment on it's effectiveness.