Former members of the obesity medicine society are considered authorities on speaking for what that group wants, because they used to be fat. The group of former fat people is actually very distinct from current fat people in ways that i don't think non fat people are, like, trange to understand. Theyr incentivs to distance themselves from their former fat selves, which means joining in on the narle judgments that thin people have of xact people and becoming one of the most vocal proponents. That's how you make sure that everybody around you knows you're not a terrible fat person any more.