There's a scene in the middle of the movie "Notting Hill" where Julia Roberts' character is eating dinner at the home of her new boyfriend's friends. Halfway through it, the hostess sitting next to her asks her what she thinks of the chicken.
"I'm a vegetarian," she answers discretely.
Not two seconds later, the host on the other side of the table loudly asks the very same question. To which she replies with a broad and sincere smile, "It's delicious!" The hostess was a little surprised, and then very impressed. She wisely opted to wait until after they'd left to break the news to her husband.
Not to continue this node unnecessarily, but I think the above exchange is exactly in the spirit of the title. Yes, she was vegetarian, but for dietary reasons and not medical or moral ones. She knew that it wouldn't kill her to eat a little chicken for one night, while eating at least a small portion would be the gracious and polite thing to do. They'd worked hard on the meal, and she had been invited at the last minute. It would, indeed, have been seen as rude of her not to eat any of it.
The fact that she scored beaucoup points with the hostess because of their brief exchange was a happy coincidence.
Incidentally, the apostle Paul tackled this same problem in Romans 14, and while there were religious dietary restrictions at play there, the principle is pretty much the same. "It is better not to eat meat or drink wine or to do anything else that will cause your brother to fall" -- and the same holds for the reverse.