Saletan writes:

And realistically, to add normal or underweight friends to your circle, you have to relegate others who are overweight. That may be bad for your fat ex-friends, who will lose your friendship as well as your thinness. But it's fine for you, since you'll have just as many friends as before.

Maybe it's not nice to speak these truths. But maybe being nice, when you should be speaking the truth—especially to your friends—is the problem.

Okay, wait: so, thin people ditch their fat friends for the sake of themselves avoiding obesity, which leaves them with "ex-friends" (or, I might argue, never-were-friends). We're agreed on that. So then, how does the "speaking hard truths, especially to your friends" fit in here?

Saletan appears to be operating under the idea that friends should become "ex-friends" when their existence threatens one's own health or happiness--fair enough; everyone has the right to choose his/her own friends, for whatever reasons he or she so chooses.

But he can't have it both ways; the cast-offs and those shunned of thin society are no longer "friends." In imparting home truths such as "lose weight or I'm sooo over you," thin people cannot be "friends" to their fat--acquaintences? hangers-on? semi-brethren?-- Not unless "friend" is defined as "a person who gives advice with the hope of securing his or her own comfort, security, and personal advancement."

And what is Saletan's suggestion for the fat rejects? That they not have friends or social networks at all? It seems to me that that, having been deprived of the delightful companionship of their thin friends, overweight people would seek solace and friendship with one another, thus leading to yet stronger and more widely distributed social networks of the sort the NEJM study cites as contributing to obesity.

Thin people: ditch your fat friends, and fat people will grow more numerous...till they overtake thin people like you...till they rule the world...

Saletan came across as somebody who changes his friends as readily as he changes his socks! I'd hate for any of my friends (fat or skinny) to think I'd be so shallow as to change friends for such a vapid reason as 'might catch fat from them'. Maybe anybody who'd give up friends for 'health' deserves neither friends nor health. May they live long only to die thin & friendless...