Hans Bader of the Competitive Enterprise Institute notes that some municipalities have banned discrimination against fat people.
Consider the several levels of absurdity. First, a majority of Americans are overweight or obese, meaning that a majority of Americans could fall into a protected class. (This is sort of like a children's sports league in which every team wins a prize. "Yes, you, too are a member of a protected class!")
Next, as any sentient being knows, being overweight is generally not a healthy quality.
So you'll have governments doing the right hand/left hand routine. One the one hand, prodding people to lose weight, whether it's simply for nanny-state purposes, or for keeping Medicaid budgets (somewhat) under control. On the other hand, you'll have government outlawing something that might actually keep obesity in check.