It's a trap, people.
Nobody really wants to feed you when they have you in for a 4-hour interview block from 10-2pm. They're not interested in your nourishment, your freaky need from protein or providing you with a nice social opportunity over rubber chicken.
But it's a trap. They don't mean it to be a trap, but it is.
You need to have a plan. Here's what you need to know when eating lunch as part of an interview process:
1. If you're not hungry after lunch is complete, you ate too much. See the rest of these notes for why. Glad you got the big meal in and strapped on the food bags. Prepare to interview with more companies, because you're not getting this job.
2. You never order anything but salad for an interview lunch. It's pretty risk free. Graze. Be hungry at the end. Only eat the small pieces of lettuce, not the ones that could start flapping and fly away.
3. You only eat when it apparent your interviewer is about to wax poetic about something he/she is passionate about. Don't get caught with food in your mouth when you're expected to talk. Wait until they're off on a rant.
4. Never go sandwich. It involves you contorting to get it in your mouth, and has some similarities to the Seinfeld episode where Jerry sees someone in a state of undress opening an jar of pickles. Related - no one wants to see you jam a sandwich into your mouth. You're not handsome or pretty when you are doing that.
5. Eat the minimum possible without being accused of not eating. You have to eat, because it's expected. Get to the minimal level of participation and don't go further. You don't get credit for doing more, but you will be punished and penalized if you go that route.
Lunch provided during your interview process? Be alert. Don't fall into the trap of eating like a normal person. They haven't invited you into the club yet.
Once they invite you, you can recommend the Golden Corral for lunch. Whatever - for now, during your interview, keep it classy.