I will say this, that when my fat calories are a higher percentage in my diet my satiety with each meal tends to last longer and I eat less calories overall.
I notice negligible changes otherwise, I think that part is the coming down to genetics micro biome and what you're eating.
>That suggests that for me, not all calories are calories.
That's way too deceiving for newbies to read cause, yes but no. Once you're out of obesity body fat ranges and into just higher than normal that's when you can see benefits from the aggregate of the tiny changes. So looking at that low level helps alot, however if you're cutting by 300-500 calories that's plenty of wiggle room to account for your metabolism handling fat better than carbs and vice versa especially when starting out.
If one not weighing everything and measuring it will make it seem much more like a calorie isn't a calorie because it's much easier to accidentally 'over eat' enough to change your hormone response to eating. Like cooking oils, they could be adding 200+ calories to your meal without you realizing it. Carbs wise a bowl of pasta is great for you but one extra scoop and boom there goes 100-200 calories, changing your average cut amount from maybe 300-500 to 100-200.
You need consistency to communicate with your body those fluctuations is what causes gains of fat.
I've also had RMR (resting metabolism rate) tests to get some idea of base metabolism and DXA (differential X-ray) scans to identify lean vs adipose tissues.[1]
The goal for me was to find a 'budget' of how many calories a week I could eat based on my level of exercise and maintain my weight. That involves spending a lot time tracking what you eat (and for me breaking up calories by fat, carbs, and protein). All to just to data analysis and to create a data driven mental model of what I could eat and how it would affect the aggregation of fat.
[1] Not sure how widely available they are but I've used Bodyspec for both (https://www.bodyspec.com/)
Fat is processed slower, so slow that the body actually starts using stored reserves at the same time if you're doing anything intensive.
Protein is used as needed and most of the excess is excreted. Some gets converted to fat or carbs by some slow process.
At least that's how I understand it. Keto diet is exactly that, eating fat and protein and little to no carbs.