I finally made a Saidit account to comment on this post. Like you are saying, there is a lot of ideological similarities between fat activism and gender ideology.

Fat activists will contort any and every experience to fit their victimization narrative. Lots of overlap with the "chronically ill" and trans activists ways of thinking, in my personal opinion.

I don't have a lot of cogent points to add to this right now besides expressing frustration. I've been fat since puberty, although my "small fat" opinion likely wouldn't matter very much. I've struggled with compulsive and binge eating and have had a lot of trouble losing weight. Not because it's physically impossible or I have a "set point", but because I have mental issues. Lol. I recently was diagnosed with an obesity related illness that's causing me a lot of pain and also means I have to manage my food and drink intake a lot more closely. After researching this illness, I found it's extremely common and it's rates are increasing as more people are becoming obese. This isn't liberation. It's sickness and death cloaked in activism.