"Shaming" fat people is becoming increasingly ridiculous in a society that as a whole promotes unthinking lifestyles, structurally encourages bad habits and unhealthy eating, and does everything it can to economically prosper off feeding people poorly and selling them diet plans at the exact same time.
It's like a Mad Magazine strip about hypocrisy. Only it's real. And everywhere.
By that same token, I think there's also an argument to be made that the "fat acceptance" organizations and movements may be playing into the hands of society, while trying to do the right thing in a misguided manner. They are attempting to respond to the hatred and scorn directed at the overweight, but rather than focus on a holistic picture about what's wrong with society, they focus on immediate defense only against mean people.
Some people approach the issue in simple terms, and think that because obesity and poor living are increasing rapidly in the west, everyone should just become more cynical, cruel, rude, and attack-oriented. I don't think that is problem solving.
Rather, the fact that such a society-wide phenomenon is spreading so fast points to sweeping problems that need to be addressed in a far more serious and objective manner than "LOL FATTIES UR STUPID CUZ U EAT LOTS". You don't change that much of society by pointing and laughing, but by engaging people.
In shorter terms, a lot of people who LOL at weight don't seem to have any interest whatsoever in the welfare of the overweight person, though they may pay lip service to it. They are just disturbed and expressing it defensively, by objectifying and dehumanizing the other.