Fat acceptance is not what we need. However, an understanding of what makes people fat, and some kind of humanity in our view towards fat people is.
Being fat is usually not about greed - it is a mental issue far more than it is a physical one. Being extremely overweight destroys your life, particularly for young people, as they are almost always ostracised and have no chance of a good social status and partner.
People don't choose that, they just don't know how to get out of the cycle. Dieting often does more harm than good, and maintaining an exercise routine for years can seem impossible to someone who can't even jog 100m. Often people overeat as comfort - how on earth is hating fat people going to improve the situation?
It shouldn't be socially acceptable, but the solution is help, not hate.
For reference, I am not fat, but I have been.