For the first 43 years of my life I was kind of always overweight. Not always obese but there were periods. I've also always known that it would be healthier to have less fat, so it was always a thing on my mind.
But, I was also always hungry. Mostly not starving, but just hungry. I could eat a big meal, that made my stomach feel physically full, even painfully so and still have the feeling of hunger.
Of course, I also understood that on pure physics terms it really is calories out vs calories in that makes the difference. So I did try to eat less.
Also, you read and see people eating a salad and at the end saying, "oh, I feel so full". I always tyhought they were lying, because that never happened to me, so I kind of dismissed it as bragging or something.
Now, could I eat less food? Yes, of course, but it's always a struggle. Every day, all day. And if you fail once, that's that week's gains gone. Imagine there's a fly that's buzzing around your face 24/7 and you can't swat it away, you just have to live with it and if you have a bad day and swat it away for just a bit, you get fat.
Some time ago I took ozempic for the first time and that's when I realized that yes, in fact, it is possible to eat a salad and feel satisified and full after that. Even after more than a year on semaglutide I'm still amazed at how little food I actually need. It kind of feels like I should have died by now due to lack of input calories. But I'm feeling great and almost to normal weight now!
For me the change of how I felt was really something I could not even have imagined before, that you could actually not think about food all the time and kindof ignore it and not really get hungry. And eat just a little and feel full. Amazing. But two years ago I could not have imagined that this is possible, as it had never been before.
This of course led to the realization that the opposite is true for some people, who have better regulation of whatever chemical makes you hungry. Apparently there are lots of people for whom feeling hungry after eating a large meal seems impossible. And since this is something they have never experienced, it's not really reasonable to expect them to understand or be able to imagine it. I wasn't able to imagine the reverse!
So yes, it is possible for everyone to lose weight just by commiting. But it is much harder to commit in a specific area for some people than others. Commiting to a lifetime of always being hungry is very very hard over the long term.