When you adopt a plant-based (vegan) diet people have questions... and you're expected to have answers. I find this happens most often in social situations where food is involved, such as going out to eat with friends, family or coworkers.
Sometimes the questions can get annoying, especially if they are redundant like the ever-popular, "Where do you get your protein?" and sometimes they are asked in a way thats emotionally charged.
The best thing to do is to be polite, calm and collected - no matter what.
Don't get defensive, or be abrasive. Answer their question with a smile.
Realize that every time someone asks you a question, they're presenting you with an opportunity to plant a seed, spark a curiosity. You've got their undivided attention, use it wisely.
Also, I find that most people are generally curious or interested. Maybe they heard of a friend of a friend that choose to eat this way or maybe they saw something online and just want to know more.
I find that most people are more receptive to the health benefits of a plant-based diet, so that's what I try to focus on. I also avoid the v-word because I think it is too emotionally and politically charged for most people. I also talk about all the positives I've experienced, how much better I feel, how much more energy I have now that I'm plant-based. People love a good testimonial!
You also have to remember that some people are set in their ways, and can be combative. That doesn't mean you have to be; and often times, you can find a way around it, to avoid conflict or confrontation with those types.
For example, a spouse of one of my sister's friends gets combative and nasty anytime they go out to dinner and Courtney gets creative with the menu i.e. "can I leave cheese off and get mushrooms instead of meat." The solution? My sister calls the restaurant ahead to ask what meals can and cannot be modified, so she avoids asking the waiter it in front of him. She simply orders and that is that. The unpleasant situation is totally avoided.
At the end of the day, remember that you may be the first encounter someone has with a plant-based diet, so always be a great example!
How do you answer questions about your lifestyle politely?