...That you've lost weight. Apparently others can see it before the individual realizes the phsyical changes themself.
While at home this summer I was walking back to our car after paying for gas to find my mom with her mouth wide open. She said she "saw it" and I looked smaller. I've only lost 25 lbs. so far (woot woot) but apparently she noticed, in addition to others. I guess my too loose about to fall down pants are a dead give away as well.
So how about you all, are others noticing your weightloss?