The traditional meal is a well-worn ritual… First, you eat a salad or perhaps soup. Then you move to the main course. After that, you have dessert.
It seems to make sense that this meal structure is ideal if you are on a diet. You could fill up with salad. That would help you eat less of the main course. And since dessert comes at the end of the meal, you might be full enough to resist the usual sweet, calorie-laden treat.