One theory I have (no idea just a theory) is that obesity and overeating are partially the result of missing nutrients.
Something close to 50% of Americans are deficient in Magnesium for instance. But there are a lot of trace minerals and nutrients and they interact to some extent.
Is it possible people are trying to get enough of "something" when they overeat and this leads to consuming too many calories? Maybe it's not a self control issue so much as you have to eat a lot of Domino's pizza to get what your body is lacking?
I'm sure there is some contribution of nutrient deficiency to obesity, nutrition is too complex to assume otherwise. However I'm not convinced it's the main driver, although the change in diet required to control intake usually improves nutrition as a side effect.
To be more concrete, the single correct part about "calories" is that the quantity matters, but the only practical road to keeping that under control is being naturally satiated, which is entirely about what you eat, everything else is a side effect of what. I know there are more complications when we are talking about people who grew up on very bad diets and have been obese all their entire lives - there's the psychological aspect and what the gut is used to that can take a long time to change - but putting that aside, the simplified extremes are:
1. You eat predominantly processed food based on carbs and sugar all day (90% of the isles in supermarkets, that also happen to be nutritionally empty but that's a another topic). You will always be hungry, because your body has been exposed to so much sugar that it never gets close to entering ketosis during the day, so as soon as you run out you immediately feel hungry. The only way to prevent overeating is pure will power, which is not sustainable for anyone, and extremely unpleasant.
2. You eat predominantly natural food, it has far higher fat and protein content, far less sugar, far less carbs. We are talking red meat, eggs, fish, milk, veg, nuts (lots of good fat). It's really hard to even intentionally over eat on these natural foods, and to eat too frequently, because it's so high in fat and protein and so low on carbs (relatively, it doesn't mean you can't have bread in your sandwich). Your body very easily enters ketosis between meals so you don't tend to get hungry easily outside of excessive exercise.
I'm a human being, I don't adhere to #2 strictly, but I try to make that my core diet, and the effects are really obvious. On the days I have some naughty cake or croissant or whatever, I notice how much hungrier I am all day, I just accept that, it's ok, I don't do it every day. Trying to control that hunger is futile and I get a taste of what it's like for all those poor obese people who unfortunately don't know this is the reason, I don't blame them, they are a product of their environment (food industry) and a lack of education.
One thing I have learned gardening is the importance of microflora. Which we also have in our guts.
Another theory I have (again, no idea if it's true) is that when people consume carbohydrates as the bulk of their diet for length of time the gut microflora changes to species that prefer those. And they signal to the person "hey, you need some dinner rolls right now!".
> when people consume carbohydrates as the bulk of their diet for length of time the gut microflora changes to species that prefer those
This is fairly well supported by studies, it even affects oral health. Although the idea of "good" vs "bad" bacteria is more to do with displacing bacteria that processes food into undesirable compounds with something more inert, e.g in the mouth the bacteria that causes tooth decay processes sugar into acid, but in some people this is naturally displaced by another bacteria that when dominant will produce a compound that kills the acid producing bacteria while producing no acid or enamel eroding compounds itself - maybe the natural dominance of that bacteria is affected by absence of excessive sugar intake over ones lifetime, or maybe it's just luck, or a bit of both... but much like gut bacteria, to actively change the dominant bacteria seems to either require a persistent and gradual change in diet, or a shorter and much harsher measure to eliminate the existing population.
Something close to 50% of Americans are deficient in Magnesium for instance. But there are a lot of trace minerals and nutrients and they interact to some extent.
Is it possible people are trying to get enough of "something" when they overeat and this leads to consuming too many calories? Maybe it's not a self control issue so much as you have to eat a lot of Domino's pizza to get what your body is lacking?