On Saturday night, there is a mitzva to 'escort' the Shabbat out with a meal referred to as melaveh malka (lit. escorting the queen). This extends Shabbat’s holy light to the meals we will eat all week. Ideally, this meal should include bread and cooked food, just like the meals on Shabbat. Someone who is not hungry can just eat food whose blessing is Mezonot, a cooked or fried food, or at a minimum, fruit. It is appropriate to remain in Shabbat clothes for melaveh malka.