Body shaming has become one of the hardest bullying that's hard to accept. I think being in a group and forum that has the same condition but want to change their lives, it's about the motivation and not only the acceptance that they're learning.
But if they're already good with their body mass and they are altogether to accept of their body and weight. I'm not sure if the bullying will be gone.
To each their own but they cannot stop people from judging them if they stop and end only for accepting of what they are. There is nothing wrong of accepting who they are right now but don't let people put you down and do something for the biggest change of their lives.
Being healthy is also wealth and this also prolongs our lifespan. And to those bullies, they should also change themselves, learn what these people are going through not just to throw some bullying.
If we see body shaming from the perspective of bullying, I think it is a phenomenon which is likely to be here to stay, specially in western culture where we have very defined standards of what beauty is, besides we also have the constant information flow of social media like instagram, people showing always how pretty they are and always showing off the best part of themselves, when in reality, what it is shown on those social media are not a reflect of reality.
Actually, I recall there was a scandal a couple of years ago about Meta/Instagram ignoring the harmful effects their applications had on teens, and how it negatively affected their self-steem. So, in a world which has such high standards of beauty and perfection it becomes very easy to shame those who are very far away from those standards.
But it is very different being fat than having a specific body type.