I've lost a bit more than a hundred (yes, 100) pounds during the last year. My social skills have improved due to an increase in my confidence.
But here is the interesting part.
People do treat me much better. I get more respect. More smiles. They think I am more intelligent, and show this by listening to what I have to say.
And even though I am an introvert, and somewhat shy, people tell me how "social" I am.
I have not changed the way I dress (jeans, t-shirt, sneakers). Though when I'm wearing exercise clothing (running shorts, a sleeveless shirt, running shoes), people are more likely to approach me.
So, this person does have a good point. We are indeed judged by our appearances. In fact, our social standing is calculated on the fly by others on how we look.
Edited to fix spelling disaster.