I noticed an online article about a study done to determine if obesity is contagious because the researchers noticed that obese people tend to associate together (See link below for article). The answer is...they don't know. But it doesn't really seem that difficult a question. First, unhealthiness seems to run in families because they all eat and live together. There are common learned behaviors and a mutual family food culture. Second, people like to feel "normal" and to be entirely honest, being obese makes you continually different around healthy people. It's little stuff that makes us feel different, but it's still there: going clothes shopping and either finding nothing to fit you while others shop, or fearing they'll see the size you're holding; going hiking, swimming, or anything involving physical activity because you fear you won't be able to keep up; going out to eat or anything involving food because you fear what others may think of you; if you simply exist because, yup, you guessed it, you're afraid of people's judgments of you.
I really shouldn't read people's comments because I always get annoyed, but I want to point out one commentator to this article. I know that this person does not in any way represent the majority of people in regards to their view of obese people. Rather, he represents exactly what we're afraid people believe.
"Maybe obese folks 'cluster' because us skinnier types find them disgusting, and don't want to be around them if at all possible. 'Fat' is unsightly. 'Obese' is revolting." -MichaelS
No one wants to be judged, especially harshly. Of course it makes sense that obese people would want to hang out with other obese people because they can expect more understanding and less judgement. It's emotionally safer. Being treated as less than a human being for any reason including your weight is demoralizing, crushing; it cuts deep in the heart. It's natural to look for people that can see the "real" you...and some of those people might just be obese too.
On an interesting (and sad) side note, the article also points out that when asked, many obese people would rather have a disease, blindness, or herpes (uh, ewww) rather than be obese. This may be a case of switching the devil you know with the devil you don't, but what, you might wonder, could drive a person to choose total blindness rather than obesity? Obesity is curable, isn't it? I saw several comments about this on the article's page. Yes, obesity is curable. Sort of. But the stigma, the struggle, the real emotional pain, the addiction...this isn't about simple overeating or not exercising enough, it's a true life-long struggle. Obese people aren't obese because we want to be this way. I know for me there are still days when it feels hopeless. I'm working hard at the gym, I'm trying to eat the right things the right way, but I still wake up some mornings and feel that I'll never make it and it'll never get better. I've been overweight since I was in elementary school, obese since high school...most of my life. I've thought about my body and been ashamed every day for the last twenty years. Would I trade it for herpes? No, of course, no...but I understand where those participants are coming from. We all, everyone, just want some understanding and a bit less judgement. (And I'll get off my soapbox now.)