So you're saying that, by having to pump harder to feed blood to all his tissue, this man's heart was not enlarged?
Hearts get larger, my friend. I've seen an enlarged heart. The thing was the size of my head. Now, you'd have to think that the liver would have to get larger to filter all the crap he ate. So there's 2 organs that, logically, HAVE to have gotten bigger to sustain this man's bulk. Also, the stomach and other gut organs would have to get larger to accomodate the processing of nutrients to sustain this man.
That's all I'm saying. I'm not saying that this accounts for the 500lbs of lean mass, but it puts it a little bit more into perspective. Plus, the water that this man had to have been holding would weigh a helluva lot, as well.
=/