i agree overweight is probably a better term in general - its more descriptive of the issue, and has no reference in name calling - no child ever insulted a class mate by calling them 'overweight'
saying someone is fat could be seen as mean, and all this 'lets speak bluntly' business could just be used as an excuse to put people down - many people excuse their acid tongue as 'just being honest' ... and its generally true but it doesn't alter the fact that they have hurt someone.
- and really, a person is not 'fat' - they have fat on them, too much of it, but its not all they are.
if someone has cancer, we don't say they are cancer.
or any other condition.
we are encouraged not to call people by their illness - such as saying someone is an asthmatic etc, but by saying they 'have asthma' - so as not to 'define' a person by it.
i remember watching some dieting show and the bloke kept calling everyone 'massive fatty' - and i laughed my head off because he was so blunt
i guess the doctor would have to try to assess what affect it woul dhave on the patient - someone would be so upset it'd be the making of them - it would encourage them - others would go straight home and stuff their faces and go into a depression.