If you want to be a fat ass, I don't really care. Just don't come whining when someone expects you to pay for 2 seats because your bellybutton is 2 seats wide, and don't try to claim that you need special seating because your bellybutton can't fit into a normal seat.
There shouldn't be grades based on weight.....however there should be laws against fat chicks wearing anything but gigantic canvas muu muus.