Non-scale victory. From what I've gleaned, it's just an acronym used by overweight people when they achieve a weight-loss related goal that isn't tied to a number on the scale. So, like, fitting into an old dress, or not needing a belt extender on an airplane. I found these comments on a Ketogenic subreddit. The subreddit caters to all information related to Ketosis, and I guess also doubles as a weight loss subreddit. /r/Keto