Originally Posted by Tom Stormcrowe

I'd have to hazard a guess of around 18-23 pounds of loose skin and deflated fat cells, Neil. We never actually lose the fat cells, they just shrink from depletion of reserves and fluid.

On a side not, that's why it's so much easier for a shrunken formerly fat person to rebound up on the weight than it is for a person who hasn't been obese, with the same diet and activity.