I think this is a good point, im guessing slim people dont think about food that much
Anecdotal, of course, but I'm "naturally" very slim and my mum and grandma are "naturally" obese.
Whenever we have these kind of discussions, the one thing that always stands out is the way we think about hunger, or deal with hunger. I don't speak for all slim people but I am hungry quite a lot, I just don't really notice it unless I'm actually thinking about it, and I don't tend to think about it a lot.
When I DO think about it, I actually probably enjoy the feeling of being mildly hungry as it seems like I'm more switched on and awake. I really hate the stuffed full feeling and actively avoid it.
I've not eaten anything today, but I didn't "realise" that until I read your post. Now I'm realising my tummy is a bit rumbly and I could eat something. I've always been this way since a child and would get reminders to eat (as well as set meal times).
I have two daughters and notice this everyday. The oldest, like me, never seems to be hungry, or if she is, she doesn't act on those cues. She eats at mealtimes (never finishes) and will rarely ask for snacks. She would struggle to pick a favourite food if you asked her.
My youngest is the exact opposite. She's constantly hungry, constantly asking for food / snacks, when is dinner going to be ready? She loves food and has too many favourites to name. I have to ask her if she is hungry or just snacky. She can also get quite emotional about it, like if dinner is going to be late she'll come through and ask 5 or 6 times getting increasingly agitated.
This is reflected in their builds, too. Oldest is really petite, and probably what healthy looked like years ago i.e you can see her ribs, and I have to take in the waist on her clothes. Youngest doesn't look overweight, but very sturdy looking and wears the next size up if I want room to grow.
Clearly this is all anecdotal but it does make me think it's not always as simple as "eat less and move more". Well, it probably IS that simple a lot of the time, but that seems to be so much easier / harder for some people than it is for others, and going by my daughters with different fathers but raised by the same parent, it seems to be more Nature than it is Nurture. Which makes you wonder how much education can really do... I know my youngest is probably going to struggle with her weight when she is older and I have no idea what I can do to really help her. For now I'm trying to teach her to recognise the difference between eating because you are hungry and eating because you are snacky, but I'm not sure if that's something that can really be learned.