Why does protein help you feel full?

Of the three macros, protein is the one that tells your brain the meal is over — loudest per calorie, longest after the plate. The mechanism runs on satiety hormones, the arithmetic runs on digestion costs, and the practical version runs on ordering: protein and fiber first, and the meal flattens itself. The GLP-1 era proved appetite is biology; protein is the food-level lever on that same system. This guided journey covers the hierarchy, the arithmetic, and the order.