Well as someone who did want to become a neuropsychologist at one point and who has a major in Psychology, specifically revolving around neuropsych (it was just too expensive at the time to do post grad study to become a neuropsychologist), I did get to do a lot of neuropsych studies during my course, and since the subject interested me I also did a lot of reading of studies outside of the course as well. As far as understanding neurotransmitters, science is just beginning to understand that many neurotransmitters are predominantly formed within the gut by microbes.  In fact 90% or more of Serotonin produced in our bodies comes from the gut and Serotonin is known to be linked with levels of happiness - a healthy gut is shown to produce happier people.  One could argue that fat people have an imbalance in their gut microbiome that affects the production of such neurotransmitters which lead to depression and anxiety due to low serotonin levels, leading to eating more to feel better (brief burst in serotonin production).  This would also explain why when people begin to eat healthier and fix their gut microbiome by feeding it better foods, that people become happier, they lose weight.  Serotonin is also linked to things like getting proper sleep and memory and learning. If I had to guess it is mechanisms such as this that we are only now learning about with the relationship between our gut microbiome and our human cells that is one of the root causes of the obesity epidemic.  Without the internal "feel good" serotonin being released, people rely on the dopamine pathway instead, which is supposed to be the "internal reward system" for doing things that are biologically good for you - like eating, fucking, exercising and taking a shit.  Unfortunately the dopamine pathway can be abused and is the main pathway responsible for addictions and it can be based in physiological affects (such as cocaine for example blocking dopamine reuptake by neurons so that the dopamine continues to make the neurons fire until no dopamine is left resulting in the extreme lows you see with drug addicts), or they can be learned and be purely psychological. Like for example being addicted to social media and getting validation from others.  There is nothing that is physiologically blocking dopamine reuptake like you get with drugs, but getting validation from other people due to humans being very social gives a big dopamine hit and makes people feel good about themselves. I mean if I had to take a guess the relationship is a lot more complex than that and we may never fully understand it, but I don't believe that the human experience can be fully explained by the purely physiological.  Experiences and learning play a huge role in the choices we make in our lives. I think social psychology would work just as well to explain why people turn their lives around to become less fat, as well as a physiological theory could.  I think it's a combination of a lot of things.  For me and my housemate at least it was finding FPH and reading fat people stories (before FPS became the dumpster fire it is today).  Seeing that being fat wasn't a result of becoming older like people told us it was, and that it was possible to be a healthy weight, and becoming aware of the reasons why is what caused us to change.  So it was really just educating ourselves about the possibilities and becoming aware of what we were doing to contribute to our problem, and then doing something about it.  Being fat just kind of creeps up on you and you don't really notice it until people start pointing it out, which is why I believe that shaming fat people does work.  It makes them aware of the problem so they can choose to do something about it. It's just that most people are compl  1000  acent and lazy, and out of touch with reality.  Most people may never have that wake up call as their bodies pass them red flag after red flag and they continue to ignore it.  Fortunately for my housemate and I we were never huge, and it took only a year or so for us to lose the weight we needed to be a healthy weight again, and since we have the tools and knowledge and awareness from that experience, becoming fat will never be a problem we have to face again :)    To be successful in something you need to be able to see the possibility of yourself achieving it. If someone you know does something then you can see that it's  possible for you to do it as well.  By disregarding and being delusional about the existence and health of people fitter than they are, fat people are refusing to see the possibility of being better than they are, instead seeking validation from others about the choices they are making and being continuously reinforced by the idea of "other people like me now so why should I change?"  If you don't have a reason to change, then there is no point in changing.  Something within them tells them that they are making the wrong choices but they choose to ignore it, you can see by the way they project that little voice in their heads onto everyone around them, even if that person isn't doing anything to them.  They know there is no reason not to be a healthy weight, but they either don't know how or choose not to change because humans like to take the path of least resistance, which is basically just to keep doing what you're doing and tell yourself that you don't care, when actually you do care, and your own biology tells you that.  It's not just social conditioning that tells you what is normal, we do have biological mechanisms in place to regulate that as well, call it instinct.    Anyway I've been rambling and I think I went off topic but the TL;DR is that fat people know it's not fine to be that big, and they abuse a lot of healthy and normal psychological mannerisms in order to justify it.  Changing your ways comes down to admitting there's a problem and being self-aware of your actions in contributing to the problem, and then changing those behaviours to fix the problem.  Fat people are just too lazy to do that, seek validation from others and justify their delusions by blaming society for their problems rather than realising the problem can be fixed if they just put in a bit of effort.