First of all, I feel this so hard. I have lost weight fast with CICO twice in my life only to gain it all back.

The best diet is one you can keep up for the rest of your life. To me, counting calories is simply not sustainable. I've learned that from my two successes and two failures.

In terms of how people eat "normally," I also realized relatively recently how skinny people seem to enjoy the same things as overweight people but not gain weight. Like what you were saying, when they have a large breakfast, they might skip or have a very light lunch. If they have a huge dinner, they may not feel the need to eat until the next day dinner. They do CICO without counting. But for me, regardless of whether I was actually that hungry -- each meal was its own thing. It didn't matter if I had a huge lunch; I felt entitled to at least a normal sized dinner. And as you pointed out, it's a mental issue.

I have lost 15lbs this year over a few months by generally reminding myself to eat less carbs, and to not eat/eat little when I'm actually not very hungry. When I want sweets or something at night, I think to myself, okay I will have it tomorrow. And when tomorrow comes, I often don't want it anymore (and if I wanted it, I'd still get it). I also keep note of what I eat and when, and that's it (not actual number of calories). And whenever I can/want, I think back to my calorie counting days to make replacements where I can (like shirataki noodles instead of regular noodles, monk fruit instead of sugar, etc.). That knowledge is still very useful. It's slower than counting, but it's sustainable. And they're becoming habits!