@Joe Nation,
At least you're a guy.
I'm kidding, actually. There were a certain bunch of years when I was single and moderately chubby in my early sixties that I suppose I became blank to some, as a woman, but in reality, I wasn't going to parties of twenty some year olds interested in each other. Those were the years I had smarty type couples interested in me as a friend. All the gotten to know men that might work were hooked up, and the rest were interesting, as were the women.
When I was in my forties and fifties, I'd plenty of people to yammer on with and sometimes flirt, though I've never been a big flirt, which is familial avoidance, far as I can figure.. plus I was married for a lot of that.
In my forties, I had a year or two of chub and maybe people dismissed me but I was too busy to notice much. In my twenties and early thirties, I had some gorgeous girlfriends. I was no dog (reminds me of a photo I took at a rest stop of a ladies room door, no dogs allowed), but was usually not the one of interest, a good thing, re pests. (I've opinions on this 'dog' business but will forgo them for now)
In my teens, I was a complicated subdued mess. Was brought out by getting a job and talking to fellow workers. At that point, I was earlier than chopped liver.
The thing about being not much noticed is that you can engage straight (not sex, quoting boomer) in a lot of different situations.