Im told to plan for 1/2 lb of food per person for a wedding reception?

I dont see how people can eat 1/2 a pound of each entree being served at my daughters wedding reception?? Is this factual?? lets say the entrees are Grilled Chicken, baked beans, potato salad, 2 different pasta salads, fresh fruit, rolls and muffins and various appetizers.. If I make a 1/2 pound for each guest they are going to consume approx. 4 pounds for each guest??? I am way way confused...somebody help!!