I've had a very long and negative history with body image - I began strict dieting at age 13 when I was already technically underweight, and have since moved through stages of fairly overweight, normal weight, underweight again, and now resting at a relatively comfortable "curvy" - and I think it's absurd that there's such negative judgment attached to being fat. When other people are ugly for whatever reason, or have really poor style, we don't hold it against them as if they are polluting the atmosphere - we might whisper to one another, wow, that person is ugly, and move on, but there's little lasting attachment of value judgment. Being fat, on the other hand, earns you lasting associations with being clumsy, slobby, unmotivated, unclean, stupid, boorish, gluttonous, greedy, selfish, and undisciplined. Which, perhaps you are overindulging and undisciplined - but what does that have to do with anyone else? The amount of Twinkies you consume has so little effect on your neighbors that it is beyond negligible, and that's coming from a Ne dominant perspective. Yes, being close friends with a fat person gives you a higher chance of getting fat, too, but it's not the fat person's responsibility to ensure you don't get fat any more than it's their responsibility to ensure you get your vehicle registration renewed.
The thing is, I read a lot of opinions from people who are skinny or normal weight, who have never experienced what it is like to live as an overweight person, who say that fatness shouldn't be accepted, and they don't understand that fatness already isn't accepted. No one thinks it's okay, guys. In no place are fat people free to walk in and feel free of their fatness. There's virtually no situation in which it wouldn't be better to be skinnier. It's painful and shaming ALL THE TIME, and for some crazy reason, it seems that many people who have never been overweight have ZERO concept of this overwhelming burden of shame that is already on an overweight person, and despite generally doing little more to earn their body weight mediocrity besides winning the genetic lottery and eating reasonably, they feel some bizarre sense of entitlement to be the "moral right" and enforce the overwhelming goodness of their not-fatness on society.
Following that, there's this idea that if we publically shame fat people, they'll suddenly get skinny. The problem is, it's not lack of social pressure that has caused fatness and it's not application of more social pressure that will cause it to go away. Fatness is a problem of a huge number of factors - on a personal level, self-discipline, time management, initiative, psychological relationship with food, physical ability, and genetics - and on a systemic level, food cost, food availability, cultural attitudes towards weight, cultural attitudes towards food, and education - and more, I'm sure. None of that is swayed by the average person being disapproving of fatness. None of it.
Furthermore, there's nothing about fat acceptance that suggests that being fat is good for your health, and no one is going to suddenly stop promoting healthy eating or exercise because the world's decided to get on board with being nicer to fat people. Yes, there have been a handful of studies done showing that slightly-overweight people can be in as good or better health than normal-weight people. That's not really surprising, honestly, and it shouldn't change anything about anyone's views. Health should be completely separate of weight. Weight is an indicator - nothing more. It's not directly related to health and it shouldn't be assumed to be directly related to health. All that fat acceptance encourages is not discriminating against fat people because they're fat. It shouldn't even be an issue. It should be a basic human right.
And the invisible part of the equation that people who have never been overweight tend not to see is how public shaming actually discourages fat people from becoming healthier, because it requires that the fat person publicly own up to their "sin", publicly address it, and publicly work to fix it. Every slip, every snuck cookie is fair game for public disapproval. A lot of people already avoid public gyms because they feel like all eyes are on them. What if all eyes were critically on them, just waiting for them to mess up? That's how it already is to be overweight. It would help to ease the culture of shame so that fat people feel okay about going to the gym, about going outside and walking, about talking about food with their coworkers and friends, about eating in sight of other people, about discussing health like they're just people with a health issue instead of people defined by their weight.
It's a bit like person-centered language in psychology. Saying "this person who is overweight" instead of "this fatty".
Guess which is more empowering. Guess which one will encourage positive change.