Initially, the thread was about making bad food more expensive in an effort to curtail the unhealthy habit and thus lead to better health outcomes and decreased health costs, an effort similar to raising the prices of cigarettes.
Now, the topic seems to revolve around the choices that obese people make and whether or not we should pay for it, which is an entirely different issue.
I don't think obese people can all be lumped into the same category. Rare examples aside (athletes, etc.), people are overweight for different reasons, and its not so easy to just say they are all like that by choice. Sure, there are the PCOS, hypothyroid, chronic steroid users, antidepressant/antipsychotic takers, but they are a small percentage. The group that I think this discussion treats the most unfairly are those who have been obese since they were children, which is a significant percentage.
There seems to be an assumption that these people aren't trying, or never tried, or haven't tried twenty times and are sick of how depressed they feel when they try and fail again. Sure, some might not try, or may have given up completely. But I think that most would love to lose weight if they could figure out how to do it. It's not as easy as diet and exercise. We're talking millions of obese people here, living in a society that glorifies the fit human body. Some might disagree, but there's just not millions of stupid, lazy people walking the earth who can't figure out how to eat less and move more.
So, when refusing care (which is essentially what you'd be doing by not paying for it, KentW speaks the truth), how can one quantify who of the millions deserves this (non)treatment, and who was fed pizza and coca-cola too much as a child? Who weighs 200lbs because they are lazy, and who weighs 200lbs because they lost 40lbs and plateaued there? Who eats junk food because they like it, and who eats it because a big bag of Better Made potato chips for $1 is a helluva lot more food to snack on than one mango?