User blog comment:Bluefox87/Regarding the aftereffects of gear 4th ch 785/@comment-5398287-20150513170717/@comment-24.235.56.170-20150514030602

There's no change in mass, his bones just contract (shrink) inversely to how much they were stretched. It's like a rubber band snapping back to its original size, only this is more extreme so it squeezes past the original size and becomes smaller. Think about the range of compression of a spring.

Incidentally, this fits perfectly with your atrophy theory. If the consequence of swollen bones is shrunken bones, the consequence of swollen muscles would be shrunken muscles.