Think for a moment about why you might actually have to be vegetarian on Mars—it's much more sustainable.
There may be a catch: If you go via the Musk empire, you might (maybe?) have to be a vegetarian. A few sites rebloggedsomething from RT that Elon Musk refuted in a tweet (which he later deleted) about a "kale-eating overlord" Musk saying only vegetarians could go.
First, that seems awfully difficult. Second, Musk is a businessman and knows that, despite the many benefits to vegetarian diets, people who don't eat meat account for a smallish percentage of the population of the "advanced nations" he says he'd market Mars colonization to.
But! Think for a moment about why you might actually have to be vegetarian on Mars—it's much more sustainable. A colleague jokes that Mars isn't all that different from suburban Phoenix, but it'll have to be a heck of a lot more careful with the way it uses its resources. (This Hacker News thread is pretty entertaining for a trip down that rabbit hole, plus a few others.)
A little over a year ago now, PETA implored Musk to lobby for a vegan Mars. His official response?
"I'm a big fan of free choice for any future Martian colony. That said, it is likely that early Mars colonists would have a mostly vegetable diet, because of the energy and space needed to raise farm animals."\n