Usually, I don't tell my patients that I'm a vegan. However, I do tell them to cut out meat from their diets. I recommend more fruits, vegetables, and whole grains, and suggest that they use meat-like foods such as veggie burgers instead.
One patient today explained that the next time he sees me he'll be making loud "baaaa"ing noises because he'll be a goat from "eating so much grass".
At least I got my point across.