My understanding is that counting calories is not helpful for fat loss. What is required is lowering insulin. Insulin is the principal hormone that causes fat storage (one of its many jobs in the human body), so a high level of insulin keeps us fat. When we eat a lot of carbohydrate, all that glucose raises our blood sugar, which is very damaging to the body, so the pancreas secretes insulin to drive the excess glucose from the blood. It goes into muscles, which metabolise it, and gets stored as fat in our fat cells.
Lowering insulin allows fat to leave our fat cells to be metabolised, and lowering our carb intake is what allows insulin to drop. Fat has almost no effect on insulin (we do need some insulin to properly use our food, but we don’t need much at all), so it is the source of energy on a low-carb, high-fat diet.
So if we eat a lot of carbohydrate, insulin rises and causes it to be taken care of, so it won’t damage our body. Fat-burning gets halted until all the excess glucose gets taken care of and the glucose emergency is over.
The amount of food we can eat depends on what we eat. A high-carb diet keeps us hungry all the time, but a low-carb, high-fat diet lets us eat until we are satisfied, and then stop eating for quite some time before we get hungry again. If we listen to our body, we will be eating enough, but not too much, and it won’t be necessary to count calories. As Dr. Eric Westman, the head of a well-known obesity clinic at Duke University, likes to say, “Calories count, but we shouldn’t count them.”