Lay out the food so everyone can see it, but do not let anyone eat any. Talk about as a group how yummy the food looks, how its good for you, etc. After the discussion ask the students if they are all full and if you should pack up the food. They will say no. Ask them why not. They will answer that you need to eat it for it to be any good to you.
Liken the real food and physical bodies to spiritual food and spiritual bodies.
Discuss what spiritual food is (the gospel). Just like we need food every day we need spiritual food every day.
This is a good thing to do as part of a refreshment for an activity.