Welcome aboard, Graeme. You are not alone in this. I've got a whole wardrobe full of pants that I can't wear because they are still too small for my waistline, but they have been joined by a few that are now too large on me. Very motivational to notice the change. Good luck!
Ron
P.S. With the nickname "grep," I didn't have to check your bio to see that you were a software engineer! Go UNIX!