I used to be a butterbeast 110+lbs heavier who never worked out; now I get some type of activity in every day. I'll try to explain from my perspective: It's basically pure jealousy with a front of false-confidence to hide it. They wish they had the motivation/willpower/etc. to be in shape but they don't, yet they still want to have the same respect and social advantages that in-shape people have without any of the work. How do they think is the best way to do this? By taking every chance they get to lecture people on how it's "okay to be fat" and "HAES" and pointing out the "dangers" of anything remotely healthy (people dying from over-exercise/protein drinks/other bullshit/etc.). Their ultimate goal is to try and promote their way of life in the public's eye by degrading how healthy people live theirs. It's a lot easier to shout your opinions in a public forum online than it is to get off the couch and take personal responsibility for your own health, so that's what they do because they're lazy. Sadly, it seems to be working across most of the US due to the rise of all the fat-acceptance bullshit, but at least we're putting up a good fight back.