Many followers of Buddhism, Hinduism, and Jainism are vegetarians
In some religions like Hinduism, does not allow its followers to eat beef as the cow is believed to be sacred in their religion.
Some religions fast, these include: Buddhism, Christianity, Islam, Judaism, Taoism, Jainism, and Hinduism. Fasting can last for just a few hours or even a few weeks
Based on what your religion forbids (ex. Pigs) and doesn't (chicken)
Orthodox Jews and some conservative Jews follow dietary laws, popularly referred to as a kosher diet which is part of their Jewish scripture.
People from different backgrounds eat different types of foods and different types of traditions