I looked this up in a couple dictionaries and was surprised to find that "waste" was taken from "growth":
ETYMOLOGY:
Middle English wast, perhaps from Old English *wæst, growth, size; see aug- in Indo-European roots
I had always figured that 'waist' had something to do with a wasting between the rib cage and the hips, but now it looks like just the opposite.
Good question! Thought provoking...
..c..