In my experience, Chinese people (from People's Republic of China) are interested in us, and fascinated by us, as outsiders. I am not sure that our relative fatness is as big an issue in any sense of possible feelings of superiority as the newness of our culture compared to theirs. I am tall (5 feet 7 inches) and have red hair, so I stand out in PRC. I speak Mandarin pretty well, which isn't initially suspected when I'm in China, and I have overheard exchanges about my being "dah," which means "big." I am not fat, but I'm not skinny, and I'm larger than most Chinese women, or men, for that matter. The overheard conversation didn't seem as much looking down on me, as surprised. I have always found Chinese people to be willing to meet me halfway, and judge me on my own individual merits.
Not sure what experiences you've had, but don't read anything in that probably isn't there.