Thin people are so afraid of fat and it makes them obnoxious. (No, not all of them, just many)
Most of us have a very human and natural fear of not being in control. We think we can ward off bad things by staying on top of stuff and making the right choices. We have a feeling of deserving what we get and getting what we deserve, especially if it's something good.
Thin people are heavily invested in the idea that they're thin because they're doing something right. And in contrast, fat people are fat because they're doing something wrong.
They think they know how they would feel in a fat body (or, in some cases, they have been fat and know how they felt). They think they would feel ugly and undesirable and miserable, they think (rightly) that they would be treated worse, and they need to believe that that could never actually happen to them. They need to feel like they've put in the effort and therefore don't deserve to be fat, and so they never will be. Fat people, on the other hand, have obviously messed up and deserve not only to be fat but to be scorned for it.
This mindset is by no means exclusive to issues of size and weight. People are out here believing in their heart that they could never become poor or homeless or sick or whatever. And sure, there's such a thing as thinking too much about the potential for travesty. We need to focus on other things besides the spectre of death to be present in life.
But when this type of denial erases the humanity of those people you refuse to identify with, it's a problem. I come across that online a lot. Thin people so convinced they're making all the right choices, that they're walking the moral path, that they're clever and successful - that they feel no respect or compassion for fat people, no need to confront anti-fat bias or discrimination, because "all they have to do is what I do". That superiority feels sooo much better than accepting that they too could become fat in this life, even despite taking steps to avoid it.
