It's not communicable from person to person, but it's certainly communicable from your environment to you.

edit: Is this such a controversial statement? Does it bear explanation?

What we eat is not solely a matter of willpower. It is influenced by what sort of food is available. It is influenced by what sort of food is easier or harder to obtain. It is influenced by how hungry we are. How hungry we are can be changed by how stressed out we are, or by what we ate yesterday, or last week, or how active we have been lately. It is even influenced by what we see others eat, what is culturally acceptable to eat.

So yeah - obesity isn't communicable from person to person like the flu is, but it is something that your environment has a huge influence on.

Somehow a person eating food can't control themselves but your desire to change their behavior is objective? Your preference for bad legislation that was transmitted to you contagiously from your environment. Perhaps you would like someone to change your environment so you take better political actions. And so on.

In medicine, communicable == infectious. Obesity is not infectious.

You are correct that people's choices depend on what options they have available and their utility function. Some people will eat pie if it is available, and some people prefer (pie, obesity) to (no pie, healthy weight).

How does hindering their choices help anyone?

And yet somehow obesity was hardly a problem for thousands of years in human history. People need to stop making excuses for their poor eating and exercising habits and take responsibility for their actions.

I think it's awfully naive to claim that the environment you're raised in has no effect on your actions later in life.

According to several studies, obesity is in fact "socially contagious" -- or at least, correlated: if a friend of yours becomes obese, you are now 57% more likely to as well.

http://www.time.com/time/health/article/0,8599,1646997,00.ht...

http://www.usatoday.com/yourlife/food/diet-nutrition/2010-11...

Facebook, Farmville, and other viral apps are "socially contagious" as well. Someone call the CDC!

You make the common but fundamental mistake that fat and fit are mutually exclusive. There are plenty of fit fatties and vice-versa.