When you are hungry or think about food your gut releases grehlin. This grehlin acts as a messenger and goes to the hypothalmus and turns on neruopeptide y, which increases your appetite and decreases your metabolic burn. Grehlin is why you are always hungry at certain times of the day as your bodys internal clock releases grehlin according to its finely tuned schedule. Grehlin levels will stay up until it receives enough nutrients to make it feel satisfied. Because it takes time for the signals to kick in eating slowly will help you to eat less overall. Grehlin levels will drop as your stomach fills and then as the grehlin levels drop you will feel satisfied enough to stop eating. It is not the grehlin itself that makes you feel hungry but by the neuropeptide y and the growth hormone it releases. Eating late at night especially carbs because your body needs grehlin to move through all the necessary stages of sleep. If you don’t get the proper progression you wont get to stage 4 which gives you a big pulse of growth hormone or to rem sleep which helps protect leptin levels.
I know this all sounds complicated but it is why the right foods at the right time and sleep and exercise are all important components for good health. Constant calorie restriction as in many fad diets keeps grehlin levels high and contributes to yoyo dieting from hunger. Insulin and grehlin go hand in hand too. If insulin levels go up grehlin levels go down. Eating complex carbs and whole grains help to keep grehlin levels manageable.