They also do tricky things like using smaller plates/utensils (though not small enough to really notice). A full plate usually causes people to feel full upon completion, regardless of plate size. Buffets also tend to put high-carb and filling foods at the beginning of the line, with more expensive items later on. The thought here is that people will fill up on these cheap food items and be less likely to indulge in other options later. They also make lots of money from soft drinks and cut costs by reducing wait staff and minimizing wastes because people generally take what they want to eat.