Being a polite host is part of convincing people to feel good about you and what you're saying. That's why there is so much entertaining (dinner, drinks, parties, etc.) in politics, sales, and international relations.

There is also at least one study[1] showing that people who have recently eaten have a more positive impression of others.

[1] Mentioned last night on the show "The Brain" on PBS, which I highly recommend.

http://www.pbs.org/the-brain-with-david-eagleman/home/