Well, the question becomes, "what do you think is fat?" If a guy thinks a 140lb and she is 5'4" woman is fat, does that mean she doesn't want to improve? Some may not consider her to be fat, and many will say she is a large whale. Yes, there are some people that do not care if they are morbidly obese, they do not care what they eat, etc. But why do you care? Especially, if you are not interested in them? How do you know if they fat woman in particular thinks it ok to be fat. I don't think any woman really thinks its ok to be fat, some just accept who they are--big women. It can be extremely difficult to lose weight--people go through pills and surgery to lose weight.
I think the concept of the thread is good, people shouldn't let themselves go physically, mentally ,etc. There are a lot of people that need to improve, not just people that are large.
If the woman gets her needs met, why do you care???