They often do, especially the HAES ones. They despise anyone who takes back their humanity, because it serves as a reminder of their own inadequacies. They'll REEEE about those before and after pictures, especially if the subject did a complete 180 from megaobeast to buff with low bf percentage (male) or lean runner type (female). They hate knowing that it is possible, because then they have to face the reality that their obesity is a choice.