There is a saying that goes “Jaisa khano anna vaisa bane mana,” or, “our thoughts are directly related to food we take.”
With this in mind, the one line basis for food selection should be “Why kill for food if we can do without killing?” Here, the two broad classifications of immobile and mobile beings come in handy. The underlying non-violent principle is to completely avoid killing mobile, living beings (from two- sensed to five-sensed) and minimize the killing and harming of one-sensed living beings, i.e. air, water, earth, plant and fire bodied living beings. The former cultivates in us a feeling of compassion towards living beings while the latter is essential to maintain healthy ecosystems.
A global conference on warming in Copenhagen established and resolved that a significant proportion of greenhouse gases can be eliminated if we all become vegetarians for one day a week. Besides this, if we realize the cruelty inflicted on animals in raising beef stock and milk animals, the creation of dairy products and the practice of mechanized butchering will repel even the staunchest eaters of meat from consuming animal based products (Shugan Chand Jain, unpublished paper, “Ahińsā / Non-violence; its dimensions and practices.”).