When I started riding I lost about 20 lbs in a couple of months. Wasn't trying to lose weight and it happened so quickly it was a bit worrisome. People asked me if I was ill. Then it plateaued and in the intervening decade or so I've put a few pounds back on. But I'm still carrying about 15 pounds less that I had been for the prior 20 years or so. (I was a lot heavier before that, but that's another story.)