I lost about 8kgs, that is about 18lbs over a four week period. So yes I did lose a lot of weight on the Camino. However this was never one of my intentions. I did not set out on the Camino to lose weight and I must admit that it never entered into my mind at any time while I was there.
I had manged, only while on the Camino de Santiago, to forget about how I looked. Most of the time I was dirty and smelly, this is what comes from walking 20-30 kms every day and wearing the same clothes over and over again, even though I washed them every day. After a few days I managed to stop caring about how I appeared to other people. Now that was great and very welcome, a real freedom. .