Yet you can logically argue against the "subsets of reality" in a fantasy setting as much as you could be for it. Like I did above. The more you actually think about how this stuff would evolve or come to be, the farther away from reality you get.
Very well. Your 'logical argument' for the dubitability of eating 3 meals a day, or anything else that isn't explicitly given, lies entirely in the lack of specified in-game information for how much the races eat, or what is required for them to be nourished. The best that can be said, from that position alone, is that we merely have no information.
Stating the falsehood of it at that point would fall under precisely the same fallacy as stating the truth of it, which is positing something where there is no information to support it.The only way you get to either, "[Non-detailed postulation X] is true" or "[Non-detailed postulation X] is false" is by either assuming that 1) Whenever information or articulated inference is not provided, the fantasy world will completely and totally deviate from any semblance of familiarity, or 2) Whenever information or articulated is not provided, the fantasy world will conform to real-world norms.
And in terms of understanding whichever fantasy in general, it is once again Occam's Razor to see that, if an in-world definition, inference, or constructable argument is not given for a particular example, then it is extremely-likely safe to assume that the particular example conforms to standards of reality. Why? For a more tangential reason, virtually all fantasy is constructed to accommodate such, and it's actually considered a good habit when creating it.
I mean, think of the things you'll have to throw into doubt by your standards, things that are never explicitly displayed or stated yet we generally assume them to be true :
Required Food Consumption
Seasons as superficially functioning in the same way
Rain as coming from the sea
six or mating in general as producing offspring
The bodily requirements of excrement
Etc, etc.
The particulars, of course, aren't important, It's the overall whole. If you really want to cast the category into doubt, then more power to you. But from a practical standpoint, I don't see what you accomplish, and from a world standpoint, you end up taking some pretty ridiculous positions.
Also to note, you can have bat-[censored] crazy things in this framework. Cue most of the insanity that is TES lore. And, if there were ever definitions given, say that rain comes from the war-tears of Kyne, or that Altmer engage in magical a-parental offspring-engineering, I would be perfectly fine with that, and depending on the subject would welcome it with open arms. But once again, you do just as much work, if not moreso, in construing it differently when no in-world conflict (as given through some form) is present.