As of this morning, I'm under 400lbs.
Or rather, I was at 402.6 after having just drunk 50oz of water, so my measured weight was about 399.2 ; and I know from experimentation that I'm retaining about 8lbs of excess water right now (I took some diuretics down to the point where I was no longer showing signs of water retention, but wasn't dehydrated. Then I "gained" 8 lbs overnight from just water).
So, I'd guess my actual, non sponged up weight, is around 390-392; down from 415 (and I wasn't retaining the water at 415).
Let's call it 23lbs.
Not bad for less than 4 weeks.