Any living being, if he terrifies other living beings, is a most wretched subject, and the king should at once kill such a disturbing element. As the wild animal is killed when it creates disturbances, similarly any man who unnecessarily kills or terrifies the jungle animals or other animals must be punished at once. By the law of the Supreme Lord, all living beings, in whatever shape they may be, are the sons of the Lord, and no one has any right to kill another animal, unless it is so ordered by the codes of natural law. The tiger can kill a lower animal for his subsistence, but a man cannot kill an animal for his subsistence. That is the law of God, who has created the law that a living being subsists by eating another living being. Thus the vegetarians are also living by eating other living beings. Therefore, the law is that one should live only by eating specific living beings, as ordained by the law of God. The Īśopaniṣad directs that one should live by the direction of the Lord and not at one's sweet will. A man can subsist on varieties of grains, fruits and milk ordained by God, and there is no need of animal food, save and except in particular cases.
(Srimad Bhagavatam-----1:17:10-11-----purport).

Another significant phrase in this verse is nātihiṁsreṇa ("with minimum violence or sacrifice of life"). Even if a devotee has to commit violence, it should not be done beyond what is necessary. Sometimes the question is put before us: "You ask us not to eat meat, but you are eating vegetables. Do you think that is not violence?" The answer is that eating vegetables is violence, and vegetarians are also committing violence against other living entities because vegetables also have life. Nondevotees are killing cows, goats and so many other animals for eating purposes, and a devotee, who is vegetarian, is also killing. But here, significantly, it is stated that every living entity has to live by killing another entity; that is the law of nature. Jīvo jīvasya jīvanam: one living entity is the life for another living entity. But for a human being, that violence should be committed only as much as necessary. A human being is not to eat anything which is not offered to the Supreme Personality of Godhead. Yajña-śiṣṭāśinaḥ santaḥ: one becomes freed from all sinful reactions by eating foodstuffs which are offered to Yajña, the Supreme Personality of Godhead. A devotee therefore eats only prasāda, or foodstuffs offered to the Supreme Lord, and Kṛṣṇa says that when a devotee offers Him foodstuffs from the vegetable kingdom, with devotion, He eats that. A devotee is to offer to Kṛṣṇa foodstuffs prepared from vegetables. If the Supreme Lord wanted foodstuffs prepared from animal food, the devotee could offer this, but He does not order to do that.
(Srimad Bhagavatam-----3:29:15-----purport).

“If one offers Me with love and devotion a leaf, a flower, a fruit or water, I will accept it.” Kṛṣṇa can accept anything offered by His devotee with devotion. An avaiṣṇava may be a vegetarian and a very clean cook, but because he cannot offer Viṣṇu the food he cooks, it cannot be accepted as mahā-prasādam. It is better that a Vaiṣṇava abandon such food as untouchable.
(Sri Caitanya Caritamrta-----2:9:53-----purport).

A Kṛṣṇa conscious person, being naturally purified, has no need of developing any other purificatory process of thought or action. On account of his being highly elevated in Kṛṣṇa consciousness, he has already acquired all the good qualities and is following the rules and regulations prescribed for the mystic yogic process. Such rules are automatically practiced by the devotees. A concrete example is the quality of nonviolence, which is considered a good qualification. A devotee is naturally nonviolent and therefore doesn't have to practice nonviolence separately. Some people seek purification by joining a vegetarian movement, but a devotee is automatically a vegetarian. He doesn't need to practice separately in this matter or to join any society for vegetarians. He is automatically a vegetarian. There are many other instances showing that a devotee needn't practice anything but Kṛṣṇa consciousness; all the good qualities of the demigods automatically develop within him. Those who are intentionally practicing to be vegetarians or to become nonviolent may have good qualifications by a material estimation, but these qualifications are not sufficient to make them devotees. A vegetarian is not necessarily a devotee, nor is a nonviolent person. But a devotee is automatically both vegetarian and nonviolent. We must conclude, therefore, that vegetarianism or nonviolence is not the cause of devotion.
(Nectar of Devotion).

The standard of life for human beings cannot be applied to animals. The tiger does not eat rice and wheat or drink cow's milk, because he has been given food in the shape of animal flesh. Among the many animals and birds, some are vegetarian and others are carnivorous, but none of them transgress the laws of nature, which have been ordained by the will of the Lord. Animals, birds, reptiles and other lower life forms strictly adhere to the laws of nature; therefore there is no question of sin for them, nor are the Vedic instructions meant for them. Human life alone is a life of responsibility.
(Sri Isopanishad).

It is wrong, however, to think that simply by becoming a vegetarian one can avoid transgressing the laws of nature. Vegetables also have life, and while it is nature's law that one living being is meant to feed on another, for human beings the point is to recognize the Supreme Lord. Thus one should not be proud of being a strict vegetarian. Animals do not have developed consciousness by which to recognize the Lord, but a human being is sufficiently intelligent to take lessons from the Vedic literature and thereby know how the laws of nature are working and derive profit out of such knowledge. If a man neglects the instructions of the Vedic literature, his life becomes very risky. A human being is therefore required to recognize the authority of the Supreme Lord and become His devotee. He must offer everything for the Lord's service and partake only of the remnants of food offered to the Lord. This will enable him to discharge his duty properly. In the Bhagavad-gītā (9.26) the Lord directly states that He accepts vegetarian food from the hands of a pure devotee. Therefore a human being should not only become a strict vegetarian but should also become a devotee of the Lord, offer the Lord all his food and then partake of such prasādam, or the mercy of God. Only those who act in this way can properly discharge the duties of human life. Those who do not offer their food to the Lord eat nothing but sin and subject themselves to various types of distress, which are the results of sin (Bg. 3.13).
(Sri Isopanishad).

Food grains or vegetables are factually eatables. The human being eats different kinds of food grains, vegetables, fruits, etc., and the animals eat the refuse of the food grains and vegetables, grass, plants, etc. Human beings who are accustomed to eating meat and flesh must also depend on the production of vegetation in order to eat the animals. Therefore, ultimately, we have to depend on the production of the field and not on the production of big factories. The field production is due to sufficient rain from the sky, and such rains are controlled by demigods like Indra, sun, moon, etc., and they are all servants of the Lord. The Lord can be satisfied by sacrifices; therefore, one who cannot perform them will find himself in scarcity—that is the law of nature. Yajña, specifically the saṅkīrtana-yajña prescribed for this age, must therefore be performed to save us at least from scarcity of food supply.
(Bhagavad-Gita----3:14-----purport).

Due to rainfall, the grass, trees and other vegetation look very green. Sometimes the grass is covered by a certain kind of red insect, and when the green and red combine with the umbrellalike mushrooms, the entire scene changes, just like a person who has suddenly become rich. The farmer then becomes very happy to see his field full of grain, but the capitalists—who are always unaware of the activities of a supernatural power—become unhappy because they are afraid of a competitive price due to abundant production. In some places certain capitalists in government restrict the farmers' production of grain, not knowing the actual fact that all food grains are supplied by the Supreme Personality of Godhead. According to the Vedic injunction, eko bahūnāṁ yo vidadhāti kāmān: the Supreme Personality of Godhead maintains this creation; therefore, He arranges for a supply of whatever is required for all living entities. When there is a population increase, it is the business of the Supreme Lord to feed the people. But atheists or miscreants do not like abundant production of food grains, especially if their business might be hampered.
(Krsna Book).

Regulation of diet and sleep is recommended herein for the yogīs. Too much eating means eating more than is required to keep the body and soul together. There is no need for men to eat animals, because there is an ample supply of grains, vegetables, fruits and milk. Such simple foodstuff is considered to be in the mode of goodness according to the Bhagavad-gītā. Animal food is for those in the mode of ignorance. Therefore, those who indulge in animal food, drinking, smoking and eating food which is not first offered to Kṛṣṇa will suffer sinful reactions because of eating only polluted things.
(Bhagavad-Gita----6:16-----purport).

As far as eating is concerned, it can be regulated only when one is practiced to take and accept prasādam, sanctified food. Lord Kṛṣṇa is offered, according to the Bhagavad-gītā (9.26), vegetables, flowers, fruits, grains, milk, etc. In this way, a person in Kṛṣṇa consciousness becomes automatically trained not to accept food not meant for human consumption, or not in the category of goodness.
(Bhagavad-Gita----6:17-----purport).