JT, if I compared a high sugar diet to smoking one cigarette, I would get similarly skewed results.
To be fair, let’s compare a sugar laden diet to a smoking habit. They’re both quite unhealthy, and cause people to die. I’d like to see a study fairly comparing the two. Even if smoking is worse, where do we draw the line between inadvisable and assur? Maybe after a high sugar diet, but maybe before smoking. Maybe in between, as you suggest, but meiheicha teisi?
Also, I once saw an article in a halacha journal written by a physician who says he tried to convince R’ Moshe to asser smoking because of the risks, but he wouldn’t. So I don’t buy that R’ Moshe would have assered had he known how dangerous it is. He did know.
The second tayna might be more reasonabis, but again, where do we draw the line? It’s not as if smoking is terribly uncommon.