Thanks for your comment, Elizabeth! Now, I don't want to argue against this movement you mention which I will check out, but my feeling is that as long as we can find adherents all of us can create a "movement" still, its proliferation doesn't make it legit. This movement, along with other current philosophies revolving around building a positive body image that can endanger your health may do more bad than good, by delaying action.
Fat is not healthy - it exposes you to a variety of health issues some life-endangering. For example, my mother who is around 55yr-old has "a bit" of visceral fat which she didn't mind too much except for esthetics. Now, during her last medical check-up, her cholesterol level was really bad. Cholesterol is asymptomatic until it's not because it leads to heart-related diseases. You know what she needs to do to address this before turning to medication? Yes, you're right. She needs to lose weight by incorporating some exercise and clean eating. She might even by lucky to reverse it and get away without medication.
So, let's look at it pragmatically: if you want to live, ditch the extra weight. Positive body image is good up to a point and trusts me, anyone can recognize a plus-size person that is not looking healthy.
You don't need to be a model to be healthy, but plus-size doesn't compute as healthy in my mind, at least. And we can agree to disagree and stay friends 🤗