I think the whole discussion is ridiculous. The weight of a person has basically no effect on the fuel consumption so there are no bases to charge by the weight.

We should be talking about charging more based on the space larger individuals need. If you need two seats then you should pay for two seats. Airlines could introduce more spacious seats that are priced accordingly. Change few economy three seat rows into two seat rows and charge 50% more on those seats because you get 50% more space.

This would be an improvement towards the other passingers as well as towards those who need more space. I am pretty sure that many people would be happy to pay more if they actually received something for the money. I don't see how you could charge an overweight person more if you still ask him to cram himself to same seat as everybody else.

At the moment you could maybe buy a business class ticket, but the space/price ratio is usually ridiculous. I believe overweight people are entitled to the same offers as everybody else so this isn't really an answer. However if special overweight seats would be introduced to the economy anyone could buy a cheapest possible ticket he can find. Then the price would just be hiked up by the 50% if one needs the 50% more spacious seat due to his size.

I know this will probably never happen but I still strongly believe that we should not talk about charging extra based on the weight. If you pay extra you should receive something for your money. If you don't get more space then the whole scheme is just discriminating way to charge overweight people more money. Other passengers still suffer, overweight people still suffer, crew still suffer.