I didn't lose a hundred pounds, but I did lose about 70, and I was surprised at having to do one thing:
Buy new socks and underwear! My clothing sizes haven't changed that much, they're just looser than before, but I was supposed I couldn't fit any of my underthings anymore!

Also, yes, on the change in shoe size. I bought a couple new pairs of those sock sneakers from Skechers, and my feet hurt a lot less. The knees are hopeless though.
But now I have real ankles that I had not seen in a really long time though.