Why you should not eat meat is also described in the oldest holy, religiose and philosophical scriptures that can be found on planet earth, like the vedic Manu-samhita and Mahabharata.
The self-created Manu has said that the man who does not eat meat, or who does not kill living creatures, or who does not cause them to be killed, is a friend of all creatures.
Manu-Samhita: Manu Smriti @ Wikipedia
“Meat can never be obtained without injury to living creatures, and injury to sentient beings is detrimental to the attainment of heavenly bliss; let him therefore shun the use of meat. Having well considered the disgusting origin of flesh and the cruelty of fettering and slaying corporeal beings, let him entirely abstain from eating flesh.”(Manu-samhita 5.48-49)