Here's a question, why exactly is it more frowned upon to be underweight, than grossly overweight? Since they are both dangerous, and one is even worse than the other from the effects it has on everyone else.
When obese you cost your country more money, health insurance costs more for others, you aren't as productive, you cost more money to keep your lard ass alive, and the food that you were jamming down your throat means that OTHERS can't use that food.
Since the Earth can only support so many animals, and the fat fuckers who gobble down several times more than they need means that there is less for other humans, and other species. I would go as far to even say that the grossly overweight should have two options: lose weight, or have no access to medical care. Either one they choose it helps the rest of the world.
That would be the end of my poorly written rant.