I eat with collegues all the time (none of them know about my surgery) and I don't eat much - they never really notice, but if they do I just say, "Oh - I had such a huge break-fast (or lunch or whatever)" or "I don't really have much of an appitite today for some reason" or "This isn't as good as I hoped it would be" or...You can insert your comment here. Even, "Guess I'm not as hungry as I thought I was" should pretty much cover it. Also - talking a lot covers the fact that you're eating so slowly. Just act like you're extremely prim and proper - never talk with your mouth full (not that you do, but it can happen during a lively discussion) - put down your fork between bites, use your napkin a lot - there are so many ways.
With dating or new friends or whatever, I'd just wait till it came up on its own. I wouldn't be like, "Yea, I'm a teacher and I HAD GBP SURGERY!" It could end up dominating the conversation for hours. I'm sure it will come up after a few dates - might have to come up before getting naked at least, but hopefully that is not the first date!! (Though I am not one to judge as I'm in a glass house on that one - albeit I've been married for 14 years!)
