... it sounds like the concept of remembering something? And that you liked that thing, and it's entirely possible to just do it again? Pretty normal stuff

For me i think it's your brain giving you an incentive to eat something you need nutrient wise, most of the time it's bog standard hunger you need calories to function and that's the fuel gauge light coming on.

But if you are needing iron maybe you want meat and you want something that fills that particular need. If a dish covers multiple bases with veggies meat and carbs it may be more generally desirable because it meets several criteria.

It's still not something i feel very strongly but i think some people experience it more because they are more in tune with the needs of their bodies.

I think this is the general formula:
The Serotonin decides (expected reward). The expectation of biggest reward in the shortest span of time with the least amount of effort and sacrifice of other things.
If time is prolonged, the reward needs to be bigger.

Being hungry moves you towards the food, not being hungry will move you towards the TV show.
If he is not that hungry he might choose the TV, but if he gets hungry while watching he might change his mind and go for the food, despite being in the middle of the show.

If money is short the dish will decline in priority, especially for people with functioning frontal lobes.
But there can be many many factors that are weighed not consciously but emotionally. Research shows we are way more guided by emotions than we think, we do what our emotions tell us, and then we rationalize it afterwards to convince our consciousness that it was in control all the time, despite it wasn't.
A significant part of our emotional state is actually controlled by bacteria in our stomach! So it is not entirely the brain alone as another comment claims. But it is signals that are sent to the brain, so in that way the brain remains the ultimate decision maker.

I've noticed the specific food craving thing around my period. It needs to replace iron or whatever, so I suddenly want a hamburger.

But how does that connection happen? Is my body releasing hormones in a specific way that my brain understands before and after the burger, and then in the future, the "give me iron" hormone is translated into fantasizing about hamburgers by my brain?

https://www.parents.com/what-to-know-about-pregnancy-cravings-7507166

I figured pregnancy was when people get weird cravings the most. Hormones go so wild then, it really makes me think hormones are the culprit here, with the brain translating them as best it can.

The like three articles I looked at on this all warned about how pica (craving for nonfood items) might mean you have low iron.

https://www.mdpi.com/2673-6357/6/3/26

The connection with iron and pica makes me think there is something concrete going on here (don't eat concrete. go see if you need iron supplements). But your hormones and brain are both flailing around trying to keep you alive, so it can get weird.

Outside eating, the craving is probably the desire to return to some feeling. Music especially seems to get associated with times and people who were around then, and specific states of mind. I permanently associated one song with a cool scene from a story I was reading, and now I get an echo of the feeling from that scene when I hear it. And when I want that reading a cool action scene feeling, I can listen to that song on purpose.

TLDR; probably brain translating desire or need by making us want things it associates with filling those needs. With food, hormones seem involved.

* Not a doctor or professional, just rambling as a lay person *

Brains are complex, but seem to boil down to input in, output out. The inputs are sensory stimuli (sights, smells, etc) as well as various hormone and other chemical levels in your body and brain. The outputs are things you think and do.

The brain will use chemicals like dopamine and serotonin to encourage behaviors. Dopamine acts like the "remember that thing? ohh that would be really good right now" messenger chemical, and serotonin is the feel good reward messenger chemical when the task completes.

Those chemicals have to actually attach to receivers in cells to work, and other chemicals can take their spot under certain conditions (this is why caffeine keeps most people from getting sleepier — it takes up the space that the "we're getting tired" messenger chemical would otherwise attach to).

* Again, not a doctor or professional, just rambling. *

But If I had to guess, some part of that process is not working as expected in your brain. Dopamine not being produced when it should be, or serotonin not attaching when it should be, or something like that. If you also experience symptoms of ADHD or depression and/or your symptoms impede your life or otherwise bother you, you should consider seeing a psychiatrist to narrow down what's actually happening and find possible solutions.

Put your hand on a hot stovetop. You'll rapidly become overwhelmed with the desire to remove it.

There's a... "activation potential" for each need and want. If it get's over the inhibitors (like, you lazing on the couch), you'd get to it.
And the wants are mostly fed by relation and wishes.
While in the case of food, it's mostly the chemical lab in your belly telling you from experience, that you need something (with more weight on calories-dense stuff (evolution), so, careful).

Well, it's a bit more complex than that (with "levels" of channels, mutual influence, etcetc), but that's the gist of it.

Evolution explains it. Hunger = need food. As we evolved, our needs got more complex and it's no longer trivial to identify specific needs from behaviors. If you crave KFC, maybe your system needs sodium, protein, and 11 other herbs and spices. Boston Legal is a popular show because it makes many people's brains produce some of the neurotransmitters they need at the moment. If you fall in love, your brain might think the person would maximize opportunities for reproducing over time. Different humans will fall in love for different reasons as their body attempts to satisfy different combinations of needs.

For me, the food I eat and stuff I watch on TV do two things: they either provide novelty and stimulation (new stuff) or comfort (old, familiar stuff).

As a person who is AuDHD (autism and ADHD), I really need both to thrive (or sometimes just exist).

So, if I feel under or overstimulated, my brain will crave whatever will help get me to equilibrium.

At least that’s how I see my system when it comes to cravings and whatnot.

Some people aren't picky at all in my experience. Like my cousin Jack. He's always ready for a meal and doesn't care what it is as long and someone else is buying/cooking!

I understand it as "brain hunger" rather than actual hunger. Ideation around food noise, you know?

Regarding activities, I usually find I crave certain activities when I get burnt out on other activities and need a break from that activity while staying occupied. For instance, if I'm doing a lot of writing at work, I may crave a spatially stimulating activity at home. It is my mind signaling I'm doing too much of one activity and I need a different one to keep from wearing out.

On my commute I like to play a game "what Iam in the mood for?" - I usually have to discard the first three things, then focus on foods I usually don't think of.
First three if interested: fried chicken, tenders chocolate bar (Milka) and cake. Tho sometimes I do play what kinda cake I would want.
Usually I end up not eating anything ftom the list - but I have fun without gaining back weight.

Probably your friend has a 'background process' that supplies him with what in the mood answers all the time.