Yet, the vast majority of obese people have perfectly working thyroids. This is not about recognizing that some medical conditions can derail your metabolism, which I believe no one is arguing, and should be covered by existing disability laws.
This is about treating all obese people, the vast majority of which are so because of their own choices, as disabled. Inability to control your own actions becomes a valid form of disability. It's a slippery slope because it legitimizes self harm and forces society to take responsibility. If obesity is a form of disability, so is tobacco or gaming dependence. And if treating obesity is not about making people eat less, then clearly treating dependence is not about smoking or gambling, we as a society should hold together and provide comfort: smoking places and breaks, subsidies for food when all the person's paycheck is lost in the casino, job protection when the addiction interferes with work performance, free medical coverage for resulting problems etc.
BTW, I write the above as a 220 pound man, who use to be as large as 260 pounds, and knows full well how hard it is for an obese person to control her appetite and weigh. But I fully understand it's MY body and MY choices, I'm fat because I love food, it's one of the great pleasures of my life and I wouldn't dream to blame nature or society for my fate.