When I was 19+ stone I had all sorts of things, all unpleasant, wrong with me that I just took for granted. It never occurred to me that they were in any way associated with being overweight. One of the less unpleasant was permanent eczema (pompholyx) on the soles of my feet - great blisters which itched like hell until I burst them with a needle.
Now I'm just over 16 stone and lots of these nasty symptoms have gone. I expect to get rid of a load more as more weight goes.
I doubt if it will get rid of my arthritis, but the less weight I can put on a dodgy joint, the better it has got to be.