I don't think a meal needs to be served, but I do agree with some of the others who have responded...a cheese/sausage tray and some veggies/dip would definitely work!
I also agree that you would want to specify that dessert is being served, so people do not assume that lunch will be served.
I also agree that you would want to specify that dessert is being served, so people do not assume that lunch will be served.