Airlines are looking at forcing obese passengers to buy two seats, and this Business Week story says one airline is looking at a fat tax.

The cattle-car quality of air travel is getting even less comfortable for some plus-size passengers. United Airlines (UAUA) on Apr. 15 announced it will require passengers who do not fit within one seat to buy another when no alternative can be arranged. And Euro-discounter Ryanair (RYAAY) is advancing the idea of a fat tax, which suggests to many observers the company may price its tickets based on body mass.

I support the idea of people paying for things based on their own risk level. There is no reason that someone who stays fit and trim should be expected to cover costs for someone who doesn’t.