I had the most humiliating experience of my life today at work.

[Warren DeMontague]

120. One, sorry you went through that.

Two, the positive takeaway is - or should be - that whatever you're doing at the gym is paying off. To the point of being unrecognizable compared to an old photo. I had some overweight years, in between my youthful metabolism letting me get away with taking shit care of myself, and when i finally got serious about health, diet, and finally regular, even religious, exercise.
What she said doesn't matter BUT it was a comment about your old picture, not the body you inhabit now.

I know for a fact that in my own case, taking care of myself pays off in terms of self esteem AND i look better, too.

Third, if you're anything like me, the way the tapes in your head run, one critical comment equals the weight of about 10,000 compliments. And BOTH criticism and compliments make you uncomfortable. (What the fuck is up with that?) The only answer ive found is to remember that that noise is, in the end, just feedback from my own brain. And then i try to remember that everyone i interact with- like this woman at your work- is likewise navigating their day through a fog of their own bullshit, assumptions, and preconceptions. This woman, for instance, was probably just trying to come up with a clever way on the fly to flirt with cute guy, and did it in a ham-fisted, foot in mouth manner that ended up making her sound mean.

If she's got any character and propensity for self-reflection, she'll feel bad for tossing out an offhanded comment that she has to know ended up being hurtful to you.

But by all means don't let her bullshit interfere with your own self improvement!