In the United States, as per guidelines, every doctor is obliged to give every patient with lifestyle problems (smoking, diet, activity) counselling on their healthy options.

I know some people are stubborn and choose not to listen to their advice. But at the end of the day, it is their own body and their own life, if they are bent on harming it, we cannot hold their hand. Our part is to make them aware and to offer help. Rest is upto their own sweet will.