Ahhhh, so this is under the guise that by dating a fat woman you are somehow choosing a path of destruction that will eventually lead to your own peril. Say, you can't get promoted at work 'cause your wife is fat. You'll get harassed 'cause your wife is fat. For the sake of your future and standing in the community bla bla bla you should avoid fat people at all costs if you know what's good for you. In essence you desire something that will place limits upon your 'mobility' in the fast paced world of the movers and shakers therefore you should resist this desire and seek counseling immediately. You must be insane to want this.
By limiting another's freedom to choose their poison we in a sense limit our own freedom to do the same via the same argument.
I think the point Jay made is very important. In today's society, acts such as smoking and unhealthy eating are becoming more and more socially unacceptable as the cost of medical care become higher and the burden on the taxpayers increases So, more and more, people resent those who are perceived as having brought on their ill health by irresponsible actions. And unfortunately, the average person still perceives fat people as being at least partially responsible for their size and resultant health problems that may be related to it. The FA who professes his desire to be with a very fat person is then opened up to similar criticism/judgement regarding the practical issues around this reality. So the judgement of the FA by others in general society is very much analogous to the judgement of the feeders that goes on in this community. Jay has nailed it.