This kink, like with most kinks, is pretty varied. Not everyone who is attracted to fat people is interested in feedism -- actually, I'd probably say that most people who are attracted to fat people aren't feedists.
But feedism does have a lot of adjacent kinks to it. Lots of people are interested in humiliation and teasing, and lots more are interested in worship and praise. Pet play is common, most often in the form of either pig or cow. A lot of people are into inflation.
Actually, I think the feedism jars work great to see a glimpse of the most commonly recurring kinks and turn-ons people have, which you can find at
feedism.neocities.org/explore/jars