It upsets me a lot, especially when people make fun of big people at the gym. Um, they're doing something about it, how do you expect them to get un-fat?? You should be supportive and encouraging. It can be VERY intimidating for a big person to go to the gym, and sometimes it takes a lot of courage. (I speak from experience).
It upsets me because people who have never had a weight problem think "oh just stop eating", they think we're all fat because we just eat too much. While that is definitely true, for a lot of people it's just not black and white like that. I have a food addiction and also emotional issues that tie in with food and eating due to being emotionally abused by my grandmother since childhood. Yes, I know if I stopped eating I wouldn't be fat, but if it were that easy, I would have done it years ago. It's a mental battle for some of us also, not just a physical one.
I don't expect people who have never had a weight problem to understand, since well, how could they? But it still upsets me.
Of course there are millions of fat people who are fat because they just like to eat and don't care to do anything about it. But we're not all that way.
Someone taking pictures of big people in the gym and making fun of them is just disgusting and immature behaviour.

I think this is the only thing "wrong" with being fat - not being able to move as efficiently and feel as good as if you were carrying less weight.

There is nothing wrong with liking food and enjoying eating. There is nothing wrong with occupying more space than someone else. And no one should be made to feel ashamed of their bodies for the way they look - or for anything, really.

There are issues that bother me more than fat bashing, but I don't ever think it's OK to discredit someone entirely based on their appearance, and I think it propagates the messed up trend of judging women solely on their looks.

I think there is nothing wrong with being fat. Eating gives you pleasure and we as humans tend to look for things that give us pleasure. Fatness in the past centuries was considered sexy. Paintings from Rubens showcase big people and their beauty

Yes, especially when some of those people could be "fat" themselves if it weren't for the miracle of great genes and a super-fast metabolism.