It’s not quite accurate.
Calories still matter, but insulin is an important part of what happens to those calories biologically and also behavior.
If you eat just fat, your insulin will remain low. When insulin is low, your body won’t store excess calories in your fat cells, and if it is low enough fat will come out of your fat cells also. If you keep eating fat, you first will feel very full because your body chemistry will signal that you have too many calories in your blood stream. For some people this triggers a need to move around and burn off the calories, or it will trigger just not eating.
This explains why overweight people often complain about being hungry or being tired even though it seems they have plenty of calories available. Because of high insulin, the calories are driven to be stored as fat and can’t escape leading to low amounts of available energy. It’s like having a gas truck run out of gas, there is plenty of gas in the tanker part but if it can’t get to the engine you are out of luck.
> Does this mean that I can consume large amount of “good fat”, regardless of it’s calories, without gaining weight?
Mostly true, but if you eat this fat with anything that causes your insulin to spike, it very quickly becomes false.
> Suppose if I replace 2 cups of milk with coconut milk, my daily calories intake would increase be almost 800 calories.
I wouldn’t worry about this too much honestly. You’ll likely get satiated earlier anyway.