I think that on a general level, this is a somewhat overly physiologically oriented view (though I totally do understand where you're coming from and I'll try to account for everything you've said in my comment; please let me know if I misunderstood anything).

The short of it is: I think the mental side of things is very often underestimated. Unfortunately the details are difficult to tease apart with actual research, so I can't back any of this up, but maybe you're interested in hearing me out anyway. In any case I promise not to turn this into a blame game.

Personal experience (so just take it as a simple counter-example without any claim to statistical relevance): I was overeating sweets for some time a few years ago. Not a TON, but a decent amount, and I put on about 10 kg (~20 lbs) over the course of, I don't know, maybe about 6 months. At some point I realized that this was becoming a trend, and so I just... stopped.

Why was that easy? As far as I can tell, it's because I was eating chocolate and such only out of convenience. It was just THERE at work. I didn't "use" it for anything. I didn't eat it to stave off boredom, comfort myself, distract myself, combat stress, or anything like that. It was enjoyable, but that was it. Not eating as much chocolate anymore didn't eliminate anything from my life that I felt I "needed". I didn't even feel bad or low-energy when I just stopped consuming the extra sweets. Similarly, for some time I drank 1.5L (about ⅓ gallon) of (sugary) soda every day but at some point I realized that I felt like it was messing me up a little so I went cold turkey on that, too, with absolutely no trouble. In both cases, I probably would have gone on just consuming these things perpetually out of habit, but it seems like my simple realization that I didn't want what they gave me, by itself, was enough to stop, and there wasn't enough of a push-back from anything to help keep the habit in place.

Of course eating/drinking something nice generates reward signals, no doubt about it... but I believe that's not the deciding factor, it's just what helps set up the dependency in the first place. Take the sense of comfort, for instance. If comfort is in short supply and you feel bad a lot, it's easy to "address" that with food and in no time you'll be conditioned to want food to feel good. If you have some sort of reason to stop but it's hard, there is probably SOME force at work that goes in the other direction, and that force might be mostly psychological.

This is also why some people will undereat despite having super tasty things at hand: psychological needs trump the basic reward of eating. The bad thing that an anorexic person THINKS the food will do is more of a deterrent than the taste (and the sugar high etc.) is a reward. If a psychological need (no matter how subtle) ALIGNS with the reward from the food, they join forces and then at some point they may become subjectively indistinguishable.

In my personal experience (I know, I know) and accounts from people I know, and posts on the internet, this pattern keeps showing up. People have a LOT more trouble quitting bad habits like overeating if other important things are missing, or out of whack, in their lives.

Now, what obscures the link further is that sometimes, we grow out of certain needs, but the conditioned habit doesn't automatically vanish. So, it's entirely possible that someone who *used* to overeat to combat an overall low mood (that's just one example, of course) ends up getting into a better place in life but the overeating still stays. This is because, to an extent, habits are self-reinforcing, because it still *feels* like the habit provides the same value that it did... and during actual short periods of low mood the impulse to fix it with eating will likely come back with a vengeance. Killing these types of self-reinforcing habits can be tough, and doing it correctly is also a bit counter-intuitive because if you pour a lot of attention onto a habit (which also happens if you try hard to fight it), you give the status quo more consciousness time which also reinforces it. Trying to fix something without focusing on it, or focusing on it in JUST the right way, is not at all easy. I know a lot of extremely unscientific tricks (that, according to my personal classification, go in the category "plausible with a scientific mindset but not supported by dependable findings because it would be very hard to test") that go in this general direction, and applying skills from practicing mindfulness is one thing actually backed up by research in various problem domains (I'm not sure about overeating – never checked – but stress is definitely on the list). Applying mindfulness skills can be hard, even if you have the baseline skills in the first place, so I like to try and figure out other tricks based on similar (and dissimilar) ideas.

I totally understand your point about the powerful link between the mind and the gut, but I don't think it's as strong of a point as it seems to be. Yes, if your gut flora is messed up, that may massively complicate things... but if that's not the actual cause (and how would we know?), then changing it won't actually affect the addiction (I avoided that term until now but I'm now going back to it as I start taking into account the physiological side of things, too), or at least not eliminate it. The trouble is this: the gut is a compelling-seeming cause of why you can't fully eliminate the impulse to eat too much, but you don't actually know that it IS, until you try a treatment. Once you do, well, maybe it works, maybe it doesn't. If it doesn't, you can always conclude that it wasn't QUITE right, and then you can keep doing it with slight variations. If it does, it could still have been a stroke of luck with placebo.

Subjective physical sensations are, unfortunately, not really a reliable indicator. For instance, being incredibly nervous or anxious often goes with a gut-sinking situation, but the gut couldn't possibly go through any substantial microbial shifts in those few seconds, right? So while it's a distinctive physiological sensation clearly coming from the gut, it doesn't quite seem reasonable to nail down the gut as the cause. As the scientists would say: correlation doesn't imply causation. I'd like to add: ... even if we know that a causal link exists some of the time, or most of the time but in a different context. In fact it's even better understood that psychological factors affect the gut, particularly when we're talking about stress. Does the link go both ways? It seems like it, but to which extent? I'm not sure we have enough understanding of that yet.

(Of course, my psychology hypothesis is just as impossible to verify with experience... until it actually works. If it ever does... I think it will, but I can't PROVE it.)

Yes, carb withdrawal is a thing. However, to the best of my knowledge, it's a thing that lasts only a few days or maybe weeks, and it's not nearly as intense as withdrawal from, you know, actual drugs. Best as I can tell, by itself it's not a sufficient explanation for being unable to kick the addiction. It's a compounding factor, for sure, but not a huge one. In fact, if this was the main factor, it could be sidestepped almost entirely by doing controlled withdrawal from excessive amounts of carbs – just turn down consumption slowly over time and you will still get withdrawal symptoms, but not nearly as pronounced. The real trouble, of course, is that it's difficult to stick to that plan – because there are the psychological factors, too, which you're familiar with in the form of those thoughts that go like "right now is a good time to deviate from the plan because X"...

So what about the other stuff you experienced, the rashes and their consequences? While arguably they could still ultimately have psychological causes, let's go with the more conventional assumption that there's a nutrition component that plays a strong factor. And that's entirely reasonable, of course. Still, the whole "these rashes make things a lot worse", paired with the "you need this diet" may just have been enough of a motivation and clear plan to help you persist with the outlined treatment despite psychological factors pulling you in the opposite direction, and enough of a deciding factor to keep your impulses in check, without the diet itself actually driving the majority of the change. Can I make any strong statements about what, exactly, caused the rash and what killed it, and how direct the link is between the rash and the gut and overeating)? No! I'm entirely willing to believe your explanation there. But I'm also willing to believe that the rashes were the result of an escalation of more diffuse physiological issues as a result of overeating and all of the attached stress, rather than being "caused" by the gut. Short of finding "reasonable proof" in the form of a definite cure (I'll explain later what I mean by that), my perspective is that it might as well not matter which of the two explanations is more accurate/relevant. We know that the changed diet helped you, that's a given. We know much less about HOW it did that.

Keeping in mind that none of this can be proved properly at this time, people who are personally affected by "addiction behaviour" (psychological dependence) will often not be quick appreciate the psychological factors because it seems like an attack on their character, or a downplaying of the difficulty they're facing. I think that this is an entirely misguided way of thinking that probably stems from the common idea that if something is "all in your head" (or even "mostly in your head"), it means that it's essentially just made up or a small thing or that you're weak for not being able to fix it, and obviously few people want to accept "weak" as a label for themselves (and I definitely support not putting yourself down!). I'm mentioning this not because I necessarily believe that's you, I just want to cover it in case you got even a tiny spark of recognition reading this, and for some additional context of why people might prefer to focus more on physiological explanations even when the overall evidence isn't clear.

Even when people accept that psychological issues aren't just about being weak or lazy or dumb or whatever, it's not so easy to actually apply that to your own situation. Let's take a radically different made up example for some analytical distance (I hope): suppose I'm scared of leaving my house. Likely that's because I believe that I'll run into situations I won't be able to handle. Maybe I'm afraid I'll be kidnapped the moment I'm out and about, or maybe I just dread having to interact with people, even if it's just walking past them.

Now, how could I handle being in that kind of state in my life? This is a non-exhaustive list of the things I believe the majority of people will try. Actual therapy is "boring" (because it might actually work) and thus I'll skip over it.

* I could just tell myself that I like being that way, or that it's "good" – internal conflict eliminated, problem "solved".
* I could tell myself that it's in my genes and it's just not possible for me to live any differently – I'd feel bad, but I could just resign myself, maybe with some proper depression on top, and that way at least I wouldn't feel conflicted anymore. Problem "solved".
* I could tell myself that I'll start going out tomorrow, this time for real, etc. This gives me the illusion of working on the problem without actually having to do it. Problem "solved".
* I could try hard to force myself to go out anyway, maybe also try and reason with my feelings. Both of those are likely to fail (sadly) and take a lot of mental energy, so most likely I won't be able to keep doing this forever, especially since it will not feel like it's actually helping me, except maybe temporarily. So, I might use it "as needed" for particularly important going-outs, but there's a chance it will get harder over time. Problem not solved but manageable... for now.
* I could just be lucky and, one day, suddenly just not have the problem anymore. This option is, unfortunately, somewhat hard to trigger, though it does happen sometimes.

Now, what else could I do on a purely mental level? Putting myself in the average person's shoes, I struggle to think of anything else that isn't a close relative of one of these. So, what are my remaining options if I want to actually solve my problem? I don't know what else to do in my mind, so I have to look at other factors. Maybe I don't believe in psychological problems in the first place, in which case I'll just skip over the above list and go straight to other factors. In either case, I might biased against getting professional help because it seems to me like I've already considered all the options that exist.

The relevant other factor for our topic is this: I could ascribe the "blame" to my physiology or brain chemistry – with anxiety and depression issues, it's extremely likely that brain chemistry will come up if you go see a psychiatrist. Now, obviously, those are INVOLVED in any serious life imbalances, because all of this stuff is connected. It's all part of the same system, after all. In fact if I started getting psychiatric medication, my anxiety might vanish completely, I could spend time experiencing situations without feeling bad and thus gain a lot of reference experience to shift my expectations and habits so that eventually the problem will actually be gone. That doesn't necessarily mean that an issue with brain chemistry CAUSED the problem, but that it can be used as an entry point to actually do something about it. Personally I'll argue that the meds are not themselves the therapy, but rather a therapeutic tool to pave the way for the actual therapy (exposure in this case), but from the average person's perspective that's probably a rather minor distinction.

However, if you accept the notion that the meds themselves aren't the therapy, this still has a failure mode: if you can interact with the anxiety-inducing situations without the actual anxiety, but all the while believe that this is ONLY due to the meds and the anxiety will return the moment you discontinue them, you're making the psychological conditioning, well, conditional. If, on the other hand, you buy into the idea that you're *habituating* to the situations and it will carry over to post-meds (or if you're just not considering this question in the first place), likely it will work out that way. Exceptions are possible, of course.

And this is one reason why it's so hard to fully understand the causes and effects: they depend on the beliefs a person brings into it. Meds will help some people fully resolve a problem, and others only temporarily (and some unlucky people might even not be helped at all). Any other approach will help some people fully resolve the problem, help others "manage" the problem, help others solve the problem but only temporarily, and be entirely useless for others.

Of course the same is true if we assume a purely physiological cause: for all we know the critical distinction that makes a treatment work or not work could be the ABC123 gene that some people have and others don't... or, to make things even more difficult to test, just the right combination(s) of genes. In the end, all we know for certain is that a given treatment X works for Y% of people, but not necessarily WHY (and "for certain" disregards various statistical complications, but let's not get into that now).

I don't think the psychological approach should be the only approach to take, but neither do I think it should be ignored or even just downplayed. Everything I've experienced says it's crucial, and I do think there is a mountain of potential on the psychological side of solving issues that we haven't really managed to "unlock" scientifically yet. Or, to put it differently: therapy is more of an art than a science... for now.

In practical terms, this makes it harder to consider it, though. It's easy to read an article that says if you'll just take vitamin Z123, your problems will go away, and then actually try it (and maybe you'll manage to placebo your way into actually solving your problem... stranger things have happened). It's not so easy to read a plethora of articles that basically all give you the same platitudes that are hard to actually apply, and then keep failing to apply them over and over (because they're not actually useful). If you decide to be more experimental, there's a limit to how many of the crazier articles actually have a non-negative value. So, if I march up to someone and start telling them about psychology, my expectation is that they'll not be entirely happy to consider it, simply because their (very reasonable) expectation is that it will be useless, based on how much they've already tried in that general direction.

I think I might be meandering a bit here so in closing (which implies a bit more structure and forethought than I actually put into this), I'll get back to one the specific things you said: being apprehensive that maybe you're better off now. This is, in my opinion, the rational thing to think based on your experience and the things you've tried and struggled with! Of course, after all this stuff you've done, you have no good reason to believe that the next random thing you'll try (or doing more of the things you've already been doing) will actually make the problem small enough that it's easily overcome even on your worst days. But the moment you do believe that, because something actually DOES completely transform the problem and you've even made it through a terrible day without struggling with the problem at all, you'll happily take a flamethrower to those old oversized clothes.

I believe it's possible to get to that point... even if I don't have a convenient silver bullet for you. Maybe I'm wrong and some sort of physiological intervention will close the subject for you for good, in which case I'll be happy for you... but don't start thinking that it's the ONLY possible way because then you'll just be stuck forever IF it turns out that none of these interventions work. Believe me, there are a LOT more psychological interventions that I can come up with by myself than physiological interventions that have even just a sliver of scientific support. Once you've exhausted all of them, I can keep going for a long time, and that's without breaking into esoteric stuff (which I have nothing to do with). Before anyone wonders, no, I don't sell therapy or self-help books or anything. This is not an ad. I just hope it might inspire some hope and willingness to explore within the boundaries of "at least it can't get worse if I try this", especially if you're out of options.

Hopefully this wall of text has been thought-provoking or otherwise useful for you, or anyone else reading this. Please feel free to follow up, call me out on things I said that you doubt, etc. Unfortunately I can't back any of this up with meaningful sources, but it doesn't actively conflict with any of the findings that I know about, and if I come across new findings I'd love to evolve it to restore that useful property.

PS. an interesting distinction to consider that I thought of while reading your comment: thought processes aren't the cognitive pattern itself, they're an EXPRESSION of the cognitive pattern. What you want to change is that pattern, not the thoughts it generates, and the best way to do that is to understand what the pattern does for you, and what will serve as a good substitute to handle the same situation very differently on a mental level. I hope this helps explain why arguing with these thoughts often does absolutely nothing useful. It CAN help, but you need to be doing the right kind of arguing. It's complicated. :-)

PS. All that aside: all the best to you!