I had a discussion with a successful thru-hiker (Ed Speer) last winter about shoe size. He mentioned that his feet had increased by several shoe sizes during his thru hike. This had turned out to be a permanent change.
I started hiking with a size 10 1/2 shoe, and have just bought my first pair of size 12 shoes. None of my old shoes fit any more.
I am interested in finding out if this is a common finding. Attached is a poll asking how much your foot size has changed with hiking - assuming your foot had stopped growing before hiking began.