Funny I had a similar problem. I didn't gain wait, but I mis-measured. Fortunately, I happened to have some leather of the correct weight, and made my own extenders. When I lost the weight, I had to take them off. That felt great, by the way.

Use extenders until you can get back down to where you were. It'll fit better once you don't need them, and you feel better when you can mothball them