meat stays in your actual stomach for longer than other foods before it moves along the digestive tract, so you are, in a sense, full for a longer period of time and it takes longer for your body to digest protein than carbs and fiber, so the meat moves along your system more slowly, telling your body that it is not hungry. Ie, you eat a candybar and it is through you in a few hours and it is simple sugar that is easily digested so it is time to be hungy again.....you eat a steak, it is in your stomach for about 4 hours then it moves along and is more difficult to break down..taking much much longer. the headache is your bodys way of saying that is needs more of something...