I was trying to find all sorts of articles etc but then it would be overwhelming, so i'm gonna say, if you need to read anything, it's just this one: Training and Diet are Simple Because Your Body is Complex

There are certainly more and less efficient ways for your body to accomplish any particular purpose, and those things certainly matter at elite levels of competition, but it’s easy to over-emphasize the differences and ignore the broad domains where pretty sizable differences in application really just don’t matter all that much for most people, most of the time.

We like to use mechanical analogies to explain our bodies. But, quite simply, those analogies just aren’t very good.

For example, a car needs a very particular type of fuel, it performs equally well until it runs out of fuel but stops functioning completely the moment it runs out, and it only has a single way of accomplishing any purpose (if one part doesn’t function correctly the whole machine stops working, or starts functioning much, much worse).

A car is linear. With a car, cause and effect are easy to unravel.

If you conceptualize your body as a linear system, it becomes much, much easier to get hung up on the details.

In a linear system, a small tweak can be the difference between optimal function and zero function. A small tweak will have predictable downstream consequences.

In a messy, nonlinear system, small tweaks are much less important. Fasted cardio? Eating six meals per day? Post-workout supplement regimens? Finding a magic rep range (that’s the topic of next week’s article)?

It’s not that those things won’t make any difference. It’s just that, if they do make a difference, the difference will probably be very small, since those things are just details, not big-picture items.

In a messy, redundant, nonlinear system, small tweaks generally get lost in the noise.

the other comments you've got are all pretty much sensible advice, and try to figure out your best way forward using the state of mind in the article I linked. fwiw that site is very popular for people into strength training, but their advice has been very sensible. your body is optimized to keep you alive - being healthy while you're alive is pretty much only a bonus. The state of the literature like I mentioned shows the variety of pathways a person can be healthy with - I mean just a couple of months ago, apparently eating ice-cream regularly is probably good for certain types of diabetes (because of how it impacts the blood sugar level). One research (I'm sharing my other forum's discussion on it, because NYT and gated academic wall) indicates that there seems to be no optimal diet really for our species, based on the various cultures studied; despite the wide range of eating habits (don't forget the indigenous people near the Arctic basically live off of seal fat), people seem to show the same general range of good health.

ETA: And in this discussion, it's about the critical baseline flaw in obesity research (and subsequent findings, preliminary or otherwise, that inform the diet and fitness industry). And if there's one outmoded 'talking point' that no one actually takes seriously on the research side, is the idea of Calorie-In-Calorie-Out. Too much contradictory evidence especially since nutrition science honestly really became a thing in the 20th century, it's only recently we're getting more proper longitudinal/long-term data from the same groups of people.