I have also lost at least a ring size. I've lost (like GONE) both my engagement ring (last year this time) and a little over a week ago, my wedding ring.

The engagement ring & wedding ring both went flying off my hand at a park last year & my husband, kids & I spent over an hour crawling around the ground looking for them. My husband kept looking after I had given up and found my wedding ring, but now it is gone too. I have been wearing a journey ring he bought me when he came back from Iraq the last time on my wedding finger, until we can afford new ones, but it is not the same. I want the old ones back.
Seriously, if your rings are lose due to weight loss... don't be an idiot like me, get them resized before it is too late!