In a word, YES.
Not everyone, and not all the time, but, as a generalization, YES. And if you are female, as I am, doubly YES.
In my mid-thirties, I gained about 30 lbs. in a relatively short period of time. This moved me, in my estimation, from “athletic” to “chubby”. All of a sudden I was invisible to men – not just socially but also in business situations, which is what really surprised me. It really forced me to question whether my success to date had been the result of my intelligence, hard work and sparkling personality ( ) or was just because of my shapely ass (again ;), but you get my drift). The response from other women was more muted, but noticeable nonetheless. And when you lose weight, a lot of people will notice and comment, which makes you think, “Wow, were they thinking I was a total blob before?” even if they say it in the nicest way.
It was an eye-opening experience and caused me to take a close look at my own reactions to larger people and make sure I wasn’t doing the same to them.
I’d like to say that this is only IME, but I’ve discussed the phenomenon with a number of female friends who had similar situations, and they all had similar experiences.
I’ll also add that this negative reaction was primarily from people who didn’t know me and only had the physical to judge by. My friends were my friends – before, during and after.
It may not be the same if you are male. We’ll see what other posters have to say.