Re: I thought I was thin.. but..
Strangely enough, yes my waist is smaller. However, my buttocks have gotten bigger. . . so I am effectively wearing the same size pants/shorts just to get it over my butt, but now the waist is loose.
A buddy of mine has a 29in waist but wears a 34in pant because of this same phenomena (he doesn't XFit, but he played college ball).