-"Why are fat people abused? Why is "fattism" seen by many as an acceptable prejudice?"
Psychoanalyst Susie Orbach explains or tries to:
Often the assumption is that overweight people have lost their self-control. That frightens society because there is so much emphasis on being slim, she says.
"Often it's not the larger person's excess weight that is the problem, it's the other people's obsession with being thin. Most people want to be slim, but this perceived physical perfection is difficult to hold on to and they fear losing control of it. Women and men can be on diets their whole lives and it's utterly miserable. They project that fear and unhappiness on to people who are bigger and that often translates into abuse and attacks. It's a way of people disassociating themselves from what they fear the most - getting fat."
But this is pure psychobabble. Like saying that all homophobes are repressed homosexuals, it's satisfying, but not true.
Most people fear cancer, but we don't "project" this fear onto others by accusing them of having it, or hating people who do have it. Orbach seems to still adhere to the Freudian idea that obvious explanations of human behaviour are usually wrong, and that people's true motives are unconscious, and usually embarrassing.
The truth is more straightforward. For various cultural and historical reasons most of us prefer thinness to fatness. And crucially we see weight as something people have personal control over. Far from fearing that overweight people have lost their self-control, we think they choose not to use it.
This is why it's "OK" to not like fat people; just as it's OK to not like criminals, selfish people, racists, etc. It's "their fault". Whereas it's not OK to make fun of people with one leg, deaf people, people with genetic disorders and so on. They "can't help it".
But there are grey areas, and this is where it gets interesting. People with cancer deserve sympathy... unless perhaps it's "their fault" for getting it, e.g. lung cancer from heavy smoking. Paedophiles deserve severe punishment... unless perhaps it's not their fault. How could it not be? How about if they developed a compulsive urge to view child porn due to the medication they were taking for Parkinson's disease? Or if they started abusing their daughter because of a brain tumour?
This is why one Kathryn Szrodecki, who campaigns on behalf of overweight people, is quoted by the BBC as saying
"We're simply not all built to be slim, our genetic make-ups are all different."
In other words: actually it's not our fault. Likewise, conservatives say homosexuality is a choice; liberals say it's something you're born being. Both sides implicitly agree that if something's not a choice, it's wrong to treat people badly for it. In an attempt to destigmatize clinical depression, a billboard famously proclaimed that "Depression is a flaw in chemistry not character" - it's not your fault.
The trend at the moment is towards things being no-one's fault. It's happened to everything from drug and alcohol addiction to antisocial and criminal behaviour (as ADHD, Conduct Disorder, Personality Disorders, etc.) By contrast, I can't think of anything which has moved in the other direction. Of course, not everyone accepts that, say, addiction is a disease. Many people still think it's a moral issue. But they're on the back foot. The wind is blowing in the other direction.
We can expect even more of this in the future, as neuroscience and genetics find biological causes and correlates of ever more behaviours. Brain scans in particular have a seductive allure when it comes to making things seem to be outside the sphere of choice. As for how valid any of this is, well, that's another story. But if the fat acceptance movement wants to advance their cause, finding a few fMRI scans might be the best way to do it.