This quote has a long history, first used in 1826 by Anthelme Brillat-Savarin, in Physiologie du Gout, ou Meditations de Gastronomie Transcendante: “Dis-moi ce que tu manges, je te dirai ce que tu es.” [Tell me what you eat and I will tell you what you are]. Later in 1863, Ludwig Andreas Feuerbach mentioned, “Der Mensch ist, was er ißt” in his essay called “Concerning Spiritualism and Materialism“.
Apart from considering the phrase for health purpose, it is also important in religious context. “Roman Catholics believe that the bread and wine of the Eucharist are changed into the body and blood of Jesus (Transubstantiation)”. Other religions do have their norms about what type of food should be consumed by disciples.
In Indian culture, food is grouped in three categories, sattvic, tamasic and rajasic. According to Ayurveda, sattvic food benefits the health (easy to digest diet) and state of mind, tamasic food also called sedative food is harmful to body and mind, and rajasic (stimulant ) food is neither beneficial nor harmful. Sattvic food includes fresh dairy products, vegetables, cereal grain, legumes, fruits and nuts in other words, natural food. Tamasic food includes meat, fish, egg, onion, garlic, scallion, leek, chive, mushroom, alcoholic beverage, blue cheese, opium and stale food. Rajasic food includes caffeinated drinks, tea, spicy food, salt, overly sweet food like energy drinks and sweets.
However, it is mentioned in the Puranas (ancient Hindu Vedic texts) that there were rishis (yogi) who were known for their high temper and they often cursed people in their anger, which is regardless of their diet.
Considering present day situation we do not see any behavioral difference among people of different diet habits. Being a vegetarian or non-vegetarian does not imply about someones being involve in a crime, or any action against laws. It is simply insane to judge people from their dietary habits.
Though it is best to eat food which is according to season, geographical location, local availability and suits a person best.