If I were to take Peikoff literally in "Fact and Value," I'd say that everything is an objective factor to your enjoyment of life. Even if we consider that to be an overreach (or even a misinterpretation on my part), I think there's some sense to it. Everything is at least potentially an objective factor to your enjoyment of life, even those things you choose to take no notice of (and equally I mean you, personally; Nerian). Even those things of which you are utterly unaware.
Yet people are limited in many ways. We are limited in our time and money and energy, our awareness and capacity to focus, etc. The resource that Howard Roark spends on architecture is resource he does not have to spend on other things, including things that are also objective factors to his enjoyment of life, and possibly including things that have "important and inescapable effects" on his quality of life. People make choices in this regard, prioritizing one thing over another, and the calculus involved (to the chagrin of many Objectivists, for some reason) is deeply personal. (Sometimes Objectivists aggrieved by this notion will describe the result as "subjective," but I prefer "individual.")
The object of your criticism, in my opinion, are those who prioritize in different ways than you do (as against those who act out of ignorance, or knowingly against their own interests, e.g. altruistically). For after all, I'd guess that these Objectivists do not pay zero attention to health or fashion -- if that were literally true, they couldn't survive for long at all, given that human health requires constant maintenance... and then you would probably know them when they stepped out of the house, if they were naked, or wearing blankets, or what-not. Some thought is given to health, insofar some choices are being made for the purpose of longevity, or to avoid sickness, etc., and some thought is given to fashion, insofar some choices are being made as to dress, though perhaps not to the degree you would select for yourself in either area.
The stereotypical image for fashion in this regard, perhaps, is the "absent-minded professor" who cannot be bothered to match his socks, but there we can see the very thing I'm talking about: he is so focused, so absorbed in his pursuits and passions that he has nothing left for caring about what he has on his feet. (Or not quite "nothing," again, given that he has managed to put something on his feet, after all, and presumably for some purpose.) You may believe that he's making a bad choice, caring insufficiently about how he "presents himself in society" -- and maybe, if you could make the case to him, he'd even agree -- but I think it's just as likely, at the least, that he would dismiss you as not caring sufficiently for his work, or for wasting your own time on how you're dressed versus other, more important pursuits. ("More important" from his perspective, you understand.)
As for "eating oneself into obesity," it seems my destiny on this board to go to bat for the value of eating ice cream, and associated pleasures, time and again. (You and I have been involved in threads where I've already expressed some of this, I know, but here is a recent discussion touching on some of these issues.) While I wouldn't recommend "obesity," as such, it cannot be denied that there is some potential cost to a life of eating ice cream, or cheesecake, or etc. Are there people we would describe as "fat" or "obese" (which, I may be mistaken, but I believe is a medical term with objective criteria) who can lead happy, productive lives? As much as you may not be able to fathom such a thing, I think so.
At the same time, are there some results so dire and inimical to what we'd otherwise describe as "the good life" that, without knowing anything else, we may condemn them as evidence of immorality? Perhaps. The people who wind up the focus of documentaries about being 900 pounds, and unable to get out of bed, come to mind. But short of that kind of extremity, I think it's unjust and dangerous to judge the choices of others sans their personal context, especially along the sorts of lines you've suggested: those insufficiently fashion-minded, etc. That isn't judgment so much as it is judgmentalism.