Religious laws have lots of "thou shalt not", but rarely any "thou shalt only in moderation". The laws of kashrut are incredibly inconvenient, but they're remarkably easy to follow in practice because they're absolute - either a food is kosher or treif, with no middle ground. You don't have to exercise judgement or restraint, you just have to blindly obey a set of well-documented rules.
Fad diets like paleo are ostensibly irrational, but they're a good fit for human psychology. Counting calories is a minefield - it's too easy to slip up, too easy to deceive yourself about the size of a portion, too easy to nibble at something while you're cooking and forget to count it. A diet that says "don't eat grains" might be theoretically sub-optimal, but it's easy to stick to and much more resistant to self-deception.
Exclusion diets also front-load the burden of self control. If you don't buy any cookies, you have to get into your car and drive to the store if you get a craving for them. If you've got a jar full of cookies, you're relying on pure self control to eat only one rather than scarfing the whole lot. They're always sitting there on the counter, tempting you to break your diet.
here's the mathematical evidence: Over a 30 year period, this intake has to be incredibly precise. In 30 years, you take in about 22 million calories (assuming 2k per day). Now, if you're off by even 5%, say 1m calories then you would gain or loose 300 pounds!! (at the well known 3400 calories per pound) The vast majority of humans and even animals, don't count their calories, so how can they eat exactly the precise amount of calories to be able to sustain roughly the same weight. The reason of course, is because while you may not be counting your calories, your body certainly is, and counting them much more precisely than you or I can. IT adjusts the amount of calories you consume to reach the target weight. Now that target weight is decided by your body's set point - YOU can not change it. If you're body tells you to eat, you must eat. And you can't just trick it by eating a ton of super low calorie spinach.
Now, you may be able to reduce your caloric intake with sheer willpower, for a day or a week, or a month or even a year. But, the body will always be trying to compensate for this. And unlike you, who will grow weary of fighting this war, biological processes don't get tired. They fight and fight just as effectively 1 year later, 5 years later or even 20 years later.
Try this experiment: just once, try to eat half the lunch you ordinarily would eat. I bet you can't do it. Just try it. And if you could do it, you would quickly realize how miserable the rest of your afternoon would be.
Everything we've done: trying to reduce our caloric intake to excessive exercising as far as loosing weight is concerned is sort of a hack. What you really want is to reduce the set point. Once you reduce your set point, loosing weight will be completely effortless. If you look at all the normal sized people, all the epdimelogical studies show: they don't excercise more and they don't eat better, their bodies simply have the correct set point.
I'm sorry but people regularly skip meals and move on with their lives. Am I missing a parody here?
All that said, I do hope someone corrects me if I'm wrong!
So it seems it is like primarily a combination of psychological and behavioral modifications that impact physiological things. If you maintain the current set point / weight for long enough, your body adjusts.
edit: I now recall a UK TV station (BBC? ITV4? sorry) that investigated how people have quite different metabolism - they monitored people with state of the art device showing how they varied quite a lot despite having the same exact diet.
https://www.nytimes.com/2012/01/01/magazine/tara-parker-pope...
https://www.nytimes.com/2016/05/08/opinion/sunday/why-you-ca...
We're not even completely sure of what causes the set point to be messed up. There's a mountain of correlational evidence that points to sugar and all the foods that were invented to replace fat (obesity skyrocketed precisly the year US told everyone to switch over from fat to sugar). But, what precisely about sugar is it? the processed foods probably?
At this point, all we can do is try to eat as natural as possible and prevent the set point from ever getting messed up, as early as possible, before your overweight before your an adult, before even childhood. It starts with the baby in the womb.
I'm not saying you're entirely wrong here; in fact, I'd agree with your premise. The issue is, that the entire idea behind consistent dieting and exercise is moving what you'd call the "set point"; but somehow you're railing against that idea in general without giving HOW to change the set point outside of consistent, mindful change.
The general problem with food/caloric intake is that it takes time for your stomach to signal that it's full; so for many people - because most eat quickly - they're actually full well before they know it, which leads to over eating. Your body doesn't "know" its fat stores, it has no way of "remembering" what your current caloric intake/output is; it's a set of feedback mechanisms that tend to handle slow processes better than fast, and the only set-point "memory" that may be involved is the feedback response for the dynamic system sitting around the saddle-points of the equation modeling the process (which is a fancy way of saying any set-point is at best a representation of a representation of a dynamic multi-variate system).
If I proscribed myself to what you're saying here; my "natural" weight gain of roughly 10 lbs per year (from 2007-2013) was because my "set point" is somewhere way, way north of 220lbs (since my weight over time didn't "hockey-stick" level off during any point before then); and once I leveled off it was because I "changed my set-point," which you never explained how to do. Or, based on empirical data, I changed my eating habits, reduced my caloric intake to something manageable for my current metabolic rate, and increased my regular exercise; thus creating a net caloric deficit to get myself to a healthy weight. Once at that healthy weight, maintaining a slower eating pace allowed me to recognize I was full before I was overfull - letting the natural feedback mechanisms actually work.
TL;DR: You're using fancy new-speak to dress up the fact that a 2KCal per day diet doesn't meet everyone's caloric balance sheet needs and people need to be mindful of their own body's needs.