Unintended eating with friends or colleagues, just for the sake of being sociable and often despite being on a strict diet. Peer pressure usually plays a role as one feels compelled to consume far more calories than planned. Similar in some ways to social drinking.
Bob: "Hey, we're going out to that new restaurant for lunch, want to join us?"
Alice: "Not really, because I'm trying to lose weight, but I will feel like an outcast if I say no."
Eve: "You're about to engage in social eating."