I think that telling a friend that they are obese will, for the foreseeable future, be something that will make the friend uncomfortable and end up causing some sort of disagreement.
Where my real issue lies is with situations like this:
http://www.cnn.com/2006/HEALTH/07/05....ap/index.html
If we get to a point where doctors can't use the word "obese," or must tread extra lightly when discussing weight issues with patients, I think we've gone too far.