Followers of Sikhism do not have a preference for meat or vegetarian consumption. There are two views on initiated or "Amritdhari Sikhs" and meat consumption. "Amritdhari" Sikhs (i.e. those that follow the Sikh Rehat Maryada - the Official Sikh Code of Conduct) can eat meat (provided it is not Kutha meat). "Amritdharis" that belong to some Sikh sects (e.g. Akhand Kirtani Jatha, Damdami Taksal, Namdhari) are vehemently against the consumption of meat and eggs.
The Sikh Gurus have indicated their preference for a simple diet, which could include meat or be vegetarian. Guru Nanak said that overconsumption of food i.e. Lobh (Greed) involves a drain on the Earth's resources and thus on life. In the case of meat, passages from the Guru Granth Sahib (the holy book of Sikhs, also known as the Adi Granth) say that fools argue over this issue. The tenth guru, Guru Gobind Singh, prohibited the Sikhs from the consumption of Kutha (any ritually slaughtered) meat because of the Sikh belief that sacrificing an animal in the name of God is mere ritualism (something to be avoided).
In Sikhism, only lacto-vegetarian food is served in the Gurdwara (Sikh temple) but Sikhs are not bound to be meat-free. The general consensus is that Sikhs are free to choose whether to adopt a meat diet or not.
Akal Takht ruling
The Akal Takht (Central Body for Sikh Temporal Affairs) represents the final authority on controversial issues concerning the Sikh Panth (community or collective). The Hukamnama (edict or clarification), issued by Akal Takht Jathedar (head priest or head caretaker) Sadhu Singh Bhaura dated February 15, 1980, states that eating meat does not go against the code of conduct (Kurehit) of the Sikhs; Amritdhari Sikhs can eat meat as long as it is Jhatka meat.
Disagreement with the ruling
Some religious sects of Sikhism—Damdami Taksal, Akhand Kirtani Jatha, Namdharis, Guru Nanak Nishkam Sewak Jatha and the 3HO—believe that the Sikh diet should be meat-free. The reason for the disagreement with this ruling is that these sects had many Vaishnav converts to Sikhism who were staunchly vegetarian.
The Akhand Kirtani Jatha dispute the meaning of the word "kutha", claiming it means all meat. However, in mainstream Sikhism this word has been accepted to mean that which has been prepared according to Muslim rituals.
Guru Granth Sahib
According to Surjit Singh Gandhi, the Guru Granth Sahib on page 472 and Guru Nanak in early 16th century said that "avoidance of flesh as food was impractical and impossible so long as they used water, since water was the source of all life and the first life principle". Guru Nanak states that all living beings are connected. Even meat comes from the consumption of vegetables, and all forms of life are based on water.
Langar
Within the gurdwara, the Guru ka Langar (Guru's community kitchen) serves purely lacto-vegetarian food because the Langar is open to all. Since people of many faiths with varying dietary taboos, and since Sikhs accept these restrictions and accommodate people regardless of their faith or culture, the Sikh Gurus adopt vegetarian food for Langar. Meat was included in langar at the time of Guru Angad, but was discontinued to accommodate Vaishnavites.
Reincarnation
Sikhism argues that the soul can possibly undergo millions of transformations as various forms of life before ultimately becoming human. These life forms could be a mineral, vegetation, or an animal. Sikhism does not see a difference between these types of existence, however the human has a privileged position compared to other life forms. In terms of the Sikh view of karma, human life is seen as being most precious, and animal, vegetable, and mineral all viewed as being equally below human life. Therefore, Sikhs view eating an animal is the same as eating a plant or mineral.
The Sikh code of conduct on the Sikh diet (Rehat Maryada)
According to the Sikh code of conduct or Rehat Maryada, Sikhs are free to choose whether or not to include meat in their diet.
The Sikh Rehat Maryada states that Sikhs cannot consume meat that is Halal (Muslim), or Kosher (Jewish).