This is a popular question... Must Hindus be Vegetarians...? If so what is the significance of being a vegetarian?
First of all, Hinduism does not have any theories of "must do" or "must not do".
In Hinduism there is a cardinal virtue called ahimsa. Cardinal means, of the greatest importance or fundamental. Ahimsa means non-violence. The practice of not hurting other living things either through physical force, words and even thoughts is the highest practice of goodness in Hinduism. A person who is able to live a life while observing all the edicts of ahimsa can be considered a saint. Our Hindu gurus and leaders such as Mahatma Gandhi are and were exponents of ahimsa. By extension of observing ahimsa, vegetarianism came to be. Whereby, the ideal practice of ahimsa inflicts no harm to life even in feeding oneself.
When it comes to rules, such as 'must I be vegetarian to be Hindu,' the answer is no. One does not need to be a vegetarian to call oneself a Hindu. This is because Hinduism does not enforce nor dictate commandments on how to live life. Rather, Hindu scriptures provide guidelines as to the ideal ways of living life and leaves it up to the devotee to 'grow' into them. In Hinduism it is accepted that as a devotee grows more and more spiritually aware, he or she will eventually become vegetarian.
In Hindu culture, to keep devotees reminded of the ideal of vegetarianism and ahimsa, Hindu families who are not vegetarians will observe vegetarianism at least once a week, (usually on the family's temple day) on a day of their choosing and also on religious festival days. I must state that the reason Hindus choose not to eat meat on certain days of the week has nothing to do with superstition or taboos. Instead, it is a practice that is observed to keep us reminded of the ideals of ahimsa, of which vegetarianism is just one of the ahimsa practices, that we should all be striving towards.
When we look at the greater observance of practicing ahimsa, controlling anger, jealousy, greed and hatred, even eradicating these impulses altogether from oneself is of far greater merit than being vegetarian. This is because performing hurtful deeds (through action, speech or even thoughts) out of anger or rage are far more destructive (meaning carrying a heavier negative karma) compared to eating meat.
Thus as Hindus, there is no force nor commandment that we must be vegetarians. However, it is an ideal that we should eventually incorporate in our life.