Comment by atmavatar

I suspect a big part of that stems from the fact that many people treat being overweight as a moral failure in and of itself, and rather than repenting and doing the morally right and correct thing to lose the weight on your own, using a GLP-1 is "cheating".

Of course, all that ignores that people's bodies are different, and some people will be slim no matter what they do, while others are doomed to be heavier regardless what they do on their own (barring extremes like developing eating disorders), but I'm not sure it would matter even should everyone understand that -- a large proportion of people need someone they perceive as lesser whom they can look down upon, and physical appearance is a quick and easy means to categorize others.