I'm also quite anti "body positivity" as it is usually espoused online, especially in relation to weight, which is by far the main focus of the movement. It feels quite self-destructive, you accept that your weight is unchangeable (even though I would say that in 75% of cases, and probably even more, it definitely isn't), and try to feel "proud" of it, even though there are piles upon piles of quite definitive research which proves that being overweight is horrible for your health, and you essentially start preventing your improvement, by choice this time. You start eating more because now you decide that you actually like being fat, now thinking that that's who you are and always will be, and you should feel proud of yourself (which is quite silly all in itself), and you just end up in a worse state than before. Body positivity will not help you get healthier.
But, we also shouldn't forget that the idea of body positivity didn't just pop up out of a vacuum, it's inherently a reaction to the culture. And here I disagree with you, if your peers and society in general just slightly nudges you to be healthy then that'd be okay, but that's not really what happens from my experience. I used to be quite overweight, especially while I was a teenager, and it was tough. People didn't really treat me like a peer, everyone avoided me, and made fun of me constantly for my weight. Random people would tell me how fat I am (by the way, I wasn't even that fat, far from obese). And in the end it fucked me up quite badly, I had no self-respect, no confidence, and I didn't really want to live at that point. I managed to turn it around, I stopped eating properly for days, often just snacking on a package of nuts for an entire day, I would start passing out when standing up, I would exercise so much until I couldn't walk anymore, and in the end it helped! I lost a ton of weight, people stopped tormenting me, and I started to be perceived as quite normal. I even had my first real boyfriend, nobody even looked at me before. But I was still miserable and felt way more unhealthy, at that point I was underweight and eating one portion of rice a day, maybe with some vegetables. No snacks or sweets of any kind. What was essentially bullying did help me to lose weight, but it did not make me healthy. That's just my personal anecdote, I bet there are people who used people making fun of them to start a journey of healthy self-improvement and honestly that's great, but I know most overweight people can't take it well. This is kind of the issue with using shame to get people to improve (though most people who hate on fat people definitely do not have that as their goal), as that shame often messes with your mental health, and makes progress way harder. Many overweight people straight up turn to food to try to feel good, just making the issue way worse. Or they get better in a self-destructive way like me. Ironically I was definitely not healthier when I was underweight, I felt physically awful most of the time, but because I looked quite normal people thought I was more healthy! Weight isn't a perfect metric for health itself, and we shame overweight people disproportionately more than underweight people (especially for women, though I bet for men it's different).
And I think a lot of people who try to follow body positivity have a similar experience to mine (at least I think so, I don't really have proof!). They have endured a ton of meanness for their weight, and often started to hate themselves because of it, and then they turn to body positivity as a sort of "Fuck you!" to the people who made them feel subhuman for their weight. And it's obviously also not productive, it's just a heavy swing in the opposite direction. It's caused directly by the shame society places upon being overweight. It's just the opposite side of the same coin, where I believe both sides suck.
- "Being fat is morally bad!"
- "No, being fat is morally good actually!"
It's kind of tough to find a good solution for this, I think we all agree that we should try to prevent as many people being an unhealthy weight as possible for the good of the people themselves and society as a whole. And I 100% don't think we should encourage people to be and stay obese just because it's easier, but making fun of people who are overweight does not actually help them either. I don't really have a solution for this. I personally try to stay "body neutral" in a way, I try to avoid putting a moral value on unhealthy weight, and I try to view it as any other health issue. But as a society, I think it makes more sense to avoid bullying fat people in the hopes that they take the bullying and turn it into nice and productive improvement, and just make being a healthy weight easier, make healthy food the easiest food to access, put value in sports and walking, and just make it easier to live a healthy life by default.
Sorry if this response kind of turned into a sob story, I thought it was important to try to offer what my own experience was like when I was experiencing the pressure to lose weight, as I know a few people who were or still are overweight who felt similarly, even if it's not universal! :)