When your stomach no longer gets wet when you do dishes - simply because it no longer lops over the sink!
When your breasts no longer rest on your stomach.
When clothing no longer cuts off your circulation! Socks, hose, cuffs, necklines...
When guys can hug you and you feel like you're being cuddled instead of strongarmed. Do you remember those hugs? Like they couldn't even get both arms around your waist... good grief.
When you can gauge everyone's size clothing because of how you've watched your own progress :P