Diet in Hinduism varies with its diverse traditions. The ancient and medieval Hindu texts recommend ahimsa—non-violence against all life forms including animals because they believe that it minimizes animal deaths. Many Hindus follow a vegetarian diet (that may or may not include eggs and dairy products), that they believe is in sync with nature, compassionate, respectful of other life forms.
Diet of non-vegetarian Hindus can include fish, poultry and goat meat in addition to eggs and dairy products. For slaughtering animals and birds for food, meat-eating Hindus often favor jhatka (quick death) style preparation of meat since Hindus believe that this method minimizes trauma and suffering to the animal. Ancient Hindu texts describe the whole of creation as a vast food chain, and the cosmos as a giant food cycle.
Hindu mendicants (sannyasin) avoid preparing their own food, relying either on alms or harvesting seeds and fruits from forests, as they believe this minimizes the likely harm to other life forms and nature.
The Vedic texts have verses that scholars have interpreted to either mean support or opposition to meat-based food.  Early Vedic texts such as the Rigveda (10.87.16), states Nanditha Krishna, condemns all killings of men, cattle and horses, and prays to god Agni to punish those who kill. The Shatapatha Brahmana (184.108.40.206) condemns the consumption of beef from cows and oxen as a sin. The Atharvaveda mentions that "rice, barley, bean, and sesamum" are the food allotted for human consumption. According to Harris, from ancient times, vegetarianism became a well accepted mainstream Hindu tradition.
While Jha and Bhaduri contend that some of the verses also support the eating of flesh, especially beef, on some occasion, Maneka Gandhi points out that in context, and consistent with other Vedic verses and the Monier-Williams Sanskrit-English Dictionary, the verses have been mistranslated. Edwin Bryant points out that although references to animal sacrifice and consumption of animal flesh is found in the Vedas, these acts were not fully accepted as there were signs of unease and tension owing to the 'gory brutality of sacrificial butchery' dating back to as early as the older Vedas. The concept of ahimsa (non-injury to living beings) is first observed as an ethical concept in the Vedas that found expression as a central tenet in Hindu texts concerned with spiritual and philosophical topics.
The Upanishads form the basis for Vedanta, which is considered the culmination of the Vedas and the philosophical paradigm of Hinduism, and support the abstention from injuring living beings, proposing ahimsa as a necessity for salvation or enlightenment (Chandogya Upanishad 8.15).
The Upanishads and Sutra texts of Hinduism discuss moderate diet and proper nutrition, as well as Aharatattva (dietetics). The Upanishads and Sutra texts invoke the concept of virtuous self-restraint in matters of food, while the Samhitas discuss what and when certain foods are suitable. A few Hindu texts such as Hathayoga Pradipika combine both.
Moderation in diet is called Mitahara, and this is discussed in Shandilya Upanishad, as well as by Svātmārāma as a virtue. It is one of the yamas (virtuous self restraints) discussed in ancient Indian texts.[note 1]
Some of the earliest ideas behind Mitahara trace to ancient era Taittiriya Upanishad, which in various hymns discusses the importance of food to healthy living, to the cycle of life, as well as to its role in one's body and its effect on Self (Atman, Spirit). The Upanishad, states Stiles, notes “from food life springs forth, by food it is sustained, and in food it merges when life departs”.
Many ancient and medieval Hindu texts debate the rationale for a voluntary stop to cow slaughter and the pursuit of vegetarianism as a part of a general abstention from violence against others and all killing of animals. Some significant debates between pro-non-vegetarianism and pro-vegetarianism, with mention of cattle meat as food, is found in several books of the Hindu epic, the Mahabharata, particularly its Book III, XII, XIII and XIV. It is also found in the Ramayana. These two epics are not only literary classics, but they have also been popular religious classics.
The Bhagavad Gita includes verses on diet and moderation in food in Chapter 6. It states in verse 6.16 that a Yogi must neither eat too much nor too little, neither sleep too much nor too little. Understanding and regulating one's established habits about eating, sleeping and recreation is suggested as essential to the practice of yoga in verse 6.17.
Another ancient Indian text, Tirukkuṛaḷ, originally written in the South Indian language of Tamil, states moderate diet as a virtuous lifestyle and criticizes "non-vegetarianism" in its Pulaan Maruthal (abstinence from flesh or meat) chapter, through verses 251 through 260. Verse 251, for instance, questions "how can one be possessed of kindness, who, to increase his own flesh, eats the flesh of other creatures." It also says that "the wise, who are devoid of mental delusions, do not eat the severed body of other creatures" (verse 258), suggesting that "flesh is nothing but the despicable wound of a mangled body" (verse 257). It continues to say that not eating meat is a practice more sacred than the most sacred religious practices ever known (verse 259) and that only those who refrain from killing and eating the kill are worthy of veneration (verse 260). This text, written before 400 CE, and sometimes called the Tamil Veda, discusses eating habits and its role in a healthy life (Mitahara), dedicating Chapter 95 of Book 7 to it. Tirukkuṛaḷ states in verses 943 through 945, "eat in moderation, when you feel hungry, foods that are agreeable to your body, refraining from foods that your body finds disagreeable". Tiruvalluvar also emphasizes overeating has ill effects on health, in verse 946, as “the pleasures of health abide in the man who eats moderately. The pains of disease dwell with him who eats excessively.”
Verses 1.57 through 1.63 of the Hathayoga Pradipika suggests that taste cravings should not drive one's eating habits, rather the best diet is one that is tasty, nutritious and likable as well as sufficient to meet the needs of one's body and for one's inner self. It recommends that one must "eat only when one feels hungry" and "neither overeat nor eat to completely fill the capacity of one's stomach; rather leave a quarter portion empty and fill three quarters with quality food and fresh water". Verses 1.59 to 1.61 of Hathayoga Pradipika suggest a mitahara regimen of a yogi avoids foods with excessive amounts of sour, salt, bitterness, oil, spice burn, unripe vegetables, fermented foods or alcohol. The practice of Mitahara, in Hathayoga Pradipika, includes avoiding stale, impure and tamasic foods, and consuming moderate amounts of fresh, vital and sattvic foods.
Charaka Samhita and Sushruta Samhita – two major ancient Hindu texts on health-related subjects, include many chapters on the role of diet and personal needs of an individual. In Chapter 10 of Sushruta Samhita, for example, the diet and nutrition for pregnant women, nursing mothers, and young children are described. It recommends milk, butter, fluid foods, fruits, vegetables and fibrous diets for expecting mothers along with soups made from jangala (wild) meat. In most cases, vegetarian diets are preferred and recommended in the Samhitas; however, for those recovering from injuries, growing children, those who do high levels of physical exercise, and expecting mothers, Sutrasthanam's Chapter 20 and other texts recommend carefully prepared meat. Sushruta Samhita also recommends a rotation and balance in foods consumed, in moderation. For this purposes, it classifies foods by various characteristics, such as taste. In Chapter 42 of Sutrasthanam, for example, it lists six tastes – madhura (sweet), amla (acidic), lavana (salty), katuka (pungent), tikta (bitter) and kashaya (astringent). It then lists various sources of foods that deliver these tastes and recommends that all six tastes (flavors) be consumed in moderation and routinely, as a habit for good health.
The Dharmasastra literature, states Patrick Olivelle, admonishes "people not to cook for themselves alone", offer it to the gods, to forefathers, to fellow human beings as hospitality and as alms to the monks and needy. Olivelle claims all living beings are interdependent in matters of food and thus food must be respected, worshipped and taken with care. Olivelle states that the Shastras recommend that when a person sees food, he should fold his hands, bow to it, and say a prayer of thanks. This reverence for food reaches a state of extreme in the renouncer or monk traditions in Hinduism. The Hindu tradition views procurement and preparation of food as necessarily a violent process, where other life forms and nature are disturbed, in part destroyed, changed and reformulated into something edible and palatable. The mendicants (sannyasin, ascetics) avoid being the initiator of this process, and therefore depend entirely on begging for food that is left over of householders. In pursuit of their spiritual beliefs, states Olivelle, the "mendicants eat other people's left overs". If they cannot find left overs, they seek fallen fruit or seeds left in field after harvest.
The forest hermits of Hinduism, on the other hand, do not even beg for left overs. Their food is wild and uncultivated. Their diet would consist mainly of fruits, roots, leaves, and anything that grows naturally in the forest. They avoided stepping on plowed land, lest they hurt a seedling. They attempted to live a life that minimizes, preferably eliminates, the possibility of harm to any life form.
The Manusmriti discusses diet in chapter 5, where like other Hindu texts, it includes verses that strongly discourage meat eating, as well as verses where meat eating is declared appropriate in times of adversity and various circumstances, recommending that the meat in such circumstances be produced with minimal harm and suffering to the animal. The verses 5.48-5.52 of Manusmriti explain the reason for avoiding meat as follows (abridged),
One can never obtain meat without causing injury to living beings... he should, therefore, abstain from meat. Reflecting on how meat is obtained and on how embodied creatures are tied up and killed, he should quit eating any kind of meat... The man who authorizes, the man who butchers, the man who slaughters, the man who buys or sells, the man who cooks, the man who serves, and the man who eats – these are all killers. There is no greater sinner than a man who, outside of an offering to gods or ancestors, wants to make his own flesh thrive at the expense of someone else's.
In contrast, verse 5.33 of Manusmriti states that a man may eat meat in a time of adversity, verse 5.27 recommends that eating meat is okay if not eating meat may place a person's health and life at risk, while various verses such as 5.31 and 5.39 recommend that the meat be produced as a sacrifice (Jhatka method). In verses 3.267 to 3.272, Manusmriti approves of fish and meats of deer, antelope, poultry, goat, sheep, rabbit and others as part of sacrificial food. However, Manusmriti is a law book not a spritiual book. So it permits to eat meat but it doesn't promote.  In an exegetical analysis of Manusmriti, Patrick Olivelle states that the document shows opposing views on eating meat was common among ancient Hindus, and that underlying emerging thought on appropriate diet was driven by ethic of non-injury and spiritual thoughts about all life forms, the trend being to reduce the consumption of meat and favour a non-injurious vegetarian lifestyle.
Hinduism does not explicitly prohibit eating meat, but it does strongly recommend ahimsa – the concept of non-violence against all life forms including animals. As a consequence, many Hindus prefer a vegetarian or lacto-vegetarian lifestyle, and methods of food production that are in harmony with nature, compassionate, and respectful of other life forms as well as nature.
India is a strange country. People do not kill
any living creatures, do not keep pigs and fowl,
and do not sell live cattle.
—Faxian, 4th/5th century CE
Chinese pilgrim to India
Hinduism does not require a vegetarian diet, but some Hindus avoid eating meat because it minimizes hurting other life forms. Vegetarianism is considered satvic, that is purifying the body and mind lifestyle in some Hindu texts.
Lacto-vegetarianism is favored by many Hindus, which includes milk-based foods and all other non-animal derived foods, but it excludes meat and eggs. There are three main reasons for this: the principle of nonviolence (ahimsa) applied to animals, the intention to offer only vegetarian food to their preferred deity and then to receive it back as prasad, and the conviction that non-vegetarian food is detrimental for the mind and for spiritual development. Many Hindus point to scriptural bases, such as the Mahabharata's maxim that "Nonviolence is the highest duty and the highest teaching", as advocating a vegetarian diet.
A typical modern urban Hindu lacto-vegetarian meal is based on a combination of grains such as rice and wheat, legumes, green vegetables, and dairy products. Depending on the geographical region the staples may include millet based flatbreads. Fat derived from slaughtered animals is avoided.
A number of Hindus, particularly those following the Vaishnav tradition, refrain from eating onions and garlic during Chaturmas period (roughly July - November of Gregorian calendar). In Maharashtra, a number of Hindu families also do not eat any egg plant (Brinjal / Aubergine) preparations during this period.
The followers of ISKCON (International Society for Krishna Consciousness, Hare Krishna) abstain from meat, fish, and fowl. The related Pushtimargi sect followers also avoid certain vegetables such as onion, mushrooms and garlic, out of the belief that these are tamas (harmful). Swaminarayan movement members staunchly adhere to a diet that is devoid of meat, eggs, and seafood.
Hindu people fast on days such as Ekadashi, in honour of Lord Vishnu or his Avatars, Chaturthi in honour of Ganesh, Mondays in honour of Shiva, or Saturdays in honour of Maruti or Saturn. Only certain kinds of foods are allowed to be eaten during the fasting period. These include milk and other dairy products such as dahi, fruit and starchy Western food items such as sago, potatoes, purple-red sweet potatoes, amaranth seeds, nuts and shama millet. Popular fasting dishes include Farari chevdo, Sabudana Khichadi or peanut soup.