Of course, it is still calorie in, calorie out, but we need to understand what effects metabolic changes in our body if we want to understand what calories are going out. Furthermore, quality of life generally indicates most people don't want to shut their metabolism down even if it did mean weight loss -- we want to be energy using machines that are motivated to "get up and do stuff", so just blindly reducing calories is not the path to that.
Calorie counting is an important part, but knowing what macro-nutrients ratio is just as important. More protein, more fat, more fiber, less carbs will help that a lot. Why is calorie tracking still so important? because fat takes forever to metabolize and is denser than carbs, so (a) You will need to break the psychological programming of expecting food to provide instant fuel, fat will take an hour(ish) to energize you; if you just are "still hungry" and eat more in 30 minutes you're losing the battle. (b) Most of us are used to eating a volume of food that equates to the calories we want from carbs. Eating that much in fat will obviously not help weight loss goals, so when eating fat dense foods we must eat much smaller portions.
There are really two separate feedback loops we use to feel sated. Fat is good