When you eat really good quality food, in small amounts, very slowly--you need less to fill you. You need less because you are being thoroughly nourished. The nutrients are there; the quality food is powerful. You're not stuffing yourself on empty junk--in effect starving your body while overloading it.
Junk food, heavily processed food, has very little nourishment in it, because it's designed just to taste good and fill your stomach. The nourishment is missing. So you end up eating a lot of it, in order to feel the least bit satisfied. You eat too much, only getting empty calories and/or a lot of fat. That makes you fatter, less nourished, and still in need of energy. So you eat more to get what you need. It’s a vicious cycle.
Quality food, well prepared, also nourishes your soul as well as your body. Savoring every bite slows down your intake, and you’ll feel fuller with less. Looking at how beautiful the food is will enliven your senses, reminding you that what you’re eating is a part of God’s beautiful creation.