There was a horrible doctor on BBC Breakfast News - don't know if she's still doing it, or if they've got the equally as bad Rosemary back - who basically propagated this, and telling young (particularly women) who had taken up smoking that their teeth were yellow, they had bad breath, their hair stank etc.
I'm sorry, but that's bullying. Making personal, judgemental comments on others under the pretext of helping them is nothing more than immature bullying. It also, in the case of young women, will only serve to further their own insecurities about themselves and do NOTHING to solve the underlying issues. From someone who was told that they were fat by multiple doctors when I was younger, it didn't shock either myself or my mother (who too is overweight) into doing anything about it, because there were other issues at play - e.g. years of bullying and social isolation, which prevented me from being active and encouraged me to stay at home all day snacking on bad things.
As another example I'd just like to give because it's suddenly jumped out at me, is that my sister went to the doctor whilst at university, who said that she had high blood pressure because she was fat. He said it in that particular way - quite nastily in fact. This led her to not eating, over exercising and led to fainting problems. Whilst she is OK now, and never got to the point of being diagnosed as anorexic, she was underweight and damaging herself because of a rather ineffectual doctor who took no consideration for her emotions and mental health before embarking on 'medical' advice. Yeah, we get it, being fat is bad for us, we can read that in the news every day. Don't gang side us further when we want and need help.