Okay, this is a toughie because generally it is a very sensitive subject! And lots of people have a tendency to sex-shame when this gets brought up, and I really, really do not want to do that. I’ve spent a little while since I got this ask mulling it over, and here’s what I’d like to say.
First of all, having a sexual fetish is not wrong. It’s not something an individual can help; what turns you on, turns you own. The problem with fetishization is that it’s labeled such because it’s “abnormal.” That’s problematic thinking right there, and the first thing I think you should do is stop thinking of what turns you on as something to be ashamed of and start thinking of it as part of your sexuality. It is what it is.
Go with me on this: I don’t think there’s anything wrong with being exclusively turned on by fat if a) you’re honest about the fact that it’s a fetish for you and b) you don’t actively objectify fat people in the natural process of, you know, living your life. There’s a difference in thinking of someone as an object and thinking of someone as a person, and objectification happens when you strip away the humanity of the person you’re looking at and think of them only as something present for your sexual gratification.
Honesty is key, here. I’d say that’s a good policy for anyone who wants to be intimate with another person. If you’re interested in being sexually intimate with a partner, you should find them sexy! That’s just, you know, good practice! And of course sexual fetishes come into play, there; that’s sort of the point of them. One of the big issues with sexual fetishization of physical characteristics is that those characteristics are attached to people. A fat fetish is in the same vein as a BDSM kink or enjoying water sports or humiliation. The tricky bit comes in that you can’t objectify handcuffs or a crop or something — it’s already an object. But you can objectify a fat person, or a person of color, or a person with really nice hair, or whatever floats your boat (I was totally serious about the hair thing; that’s a real fetish).
So you know, when you eventually talk about these things as, in a healthy and happy relationship, you should, be honest. Some people are going to be totally A-OK with it, and it might make others very uncomfortable. Fetishes are, I think, generally for you and your partner(s) to work out, not for anyone else to police. I think that a lot of the ire in the fat acceptance community comes from the fact that many fat fetishists are fucking assholes about it, routinely objectifying fat people (specifically fat women) as stereotyped objects with no humanity, and moreover, react like giant douchebags when they’re called out on it. They are actively fetishizing fat people as objects. I think there’s a difference between that and having a fat fetish.
Those are my thoughts on the matter. I know that my opinion here may not be the popular one, and I’d be totally willing to have a conversation about it.