I have mixed feelings about this film and I'd like to see it before I offer up my own two cents, but if anyone wants to read a review from an actual fat person (I am not assuming here, the critic describes herself as such in the piece) here is a review from Little White Lies that I found really empathetic and thoughtful.
I do think we should remember that this is a film about an eating disorder, a man who has basically decided to commit a slow suicide through eating the way some do through starvation. So it's not just a "har-dee-har look at this fat guy" movie, but one about great pain. Arronofsky is very hit or miss for me, but he is very interested in exploring body extremity (see also: Black Swan, The Wrestler, Requiem for a Dream). I'm very interested to see how I feel about this one once it's out, but the discourse is already proving to be quite a lot.