It's like when all the prisoners in Orange is the new Black start to claim they are Jewish in order to get the nicer Kosher meals from the cafeteria.
most airlines that fly long routes offer a ton of different menus: kosher, halal, vegetarian, vegan, asian vegetarian (my favorite - usually indian food, which still tastes good when microwaved as opposed to a lot of non-first-class airline meals), lactose-free, gluten-free, diabetic-friendly... many options available that are usually a cut above the typical "chicken or beef".
beware - you have to do this for each leg of a flight with layovers! i've occasionally had luck requesting a vegetarian or vegan meal in-flight but most of the time they only pack as many as are requested ahead of time.