If we publicly shame fat people then they can't serve as role models for younger potential fatties. It may encourage fats to lose weight. This will also create new jobs as more people will be going to the gym, therefore more gyms will open.
More all you can eat buffets will open, as there will be less fat people to take advantage of the "all you can eat" deal.
The NHS and other health services will have less strain on them, meaning waiting rooms will be less filled. If the shaming kicks off globally, other countries may even be able to justify having free health care without the fats around. This will increase health globally.
There might be enough food left for Africa to finally eat.
Its not our problem to shame on them, if they want to shame then they will. Its not our body and not our problem either. It their choice to keep eating and not to lose weight. Us as americans have so much fast foods why shame on the fat people and not on the fast food reseraunts that are making them fat.