Our temperaments are determined by a combination of the three gunas – sattva guna, rajo guna and tamo guna. Sattva guna is the highest and most sublime. It manifests itself as wisdom and serenity. Rajo guna manifests itself as dynamism and ambition. Tamo guna manifests itself as laziness and delusion.

7th verse: “The food that we eat is linked to the three gunas. The way we practice rituals, austerity and charity is also linked to the three gunas.”

The Chandogya Upanishad contains the first important discussion on the effect of what we eat and the true meaning of food. Shankaracharya has also written commentaries on the broader meaning of food. Food is not just hat we eat with mouth – our mind also eats food. It is all the ideas and associations that we imbibe and that impact our emotions and feelings. The five senses of perception and the sense objects – they all bring food to the mind.

The verse in Chandogya Upanishad is:
आहार शुद्धौ सत्त्व शुद्धिः सत्त्व शुद्धौ स्मृतिः ध्रुवा स्मृति लम्भे सर्व ग्रन्थीनां विप्र मोक्षः || [7.26.2]
It means: “From purity of food comes purity of mind. From purity of mind comes constant remembrance of higher spiritual ideas. From constant remembrance of higher spiritual ideas comes liberation from bondage.”

We remember what we are interested in. What are we are interested in depends on the structure of the mind. Whatever the mind has in its system, it wants more of it. If the mind is pure, it remembers and imbibes higher spiritual ideas.

In a broader sense, mind refers to Antahkarana, which is made up of four compartments (mind, intellect, memory system, ego sense). In darkness, we may speculate whether something is a pillar or a human – this comes from mind, which is the speculative faculty. When we conclusively determine that it is a pillar, it comes from the intellect which is the determining faculty. We may remember that we had seen a similar pillar elsewhere – that comes from chittam, which is the memory system. And then we may think “I am the one who saw it” – that comes from ahamkara, which is the ego sense.

8th verse: “Foods that enrich vitality, energy, strength, health, cheerfulness, mental equilibrium, appetite, contentment, and which are nourishing and agreeable, are liked by those endowed with Sattva guna.”

Bhagavata Purana emphasizes that we should only eat what we need for our health and sustenance. It says: “One should only eat what the system permits to eat. Those who eat more, fall sick and become a liability to themselves.” In a broader sense it also means: “Those who are greedy and keep things which they do not need and which belong to others, such people are thieves.”

There is an ancient ayurvedic verse from Sushruta Samhita, which defines health in a universal sense.
“sama dosha sama agnischa sama dhatu mala kriyaaha| Prasanna atma indriya manaha swastha iti abhidheeyate”

It means that a man is in perfect health when he is physically, mentally, spiritually and emotionally healthy. In particular, this verse emphasizes that physical health needs to be complemented with a pleasantly disposed and contented mind, senses and spirit. They should not remind us of their existence.

Manu Smriti defines what is the wrong type of food. It says:
ANAROGYAM ANAYUSYAM ASVARGYAM CA ATIBHOJANAM APUNYAM LOKA VID VISTAM TASMAT TAT PARIVARJAYET (MANU SMRITI 2/57)

It means: “One should avoid the following: (1) Food that is not good for health (2) Food that reduces the duration of life (3) Food does not guarantee good health in next life (4) Eating too much (5) Food that makes us do sinful deeds (6) Food that causes people to ridicule you.”

Food has both a gross and subtle dimension. At a gross level, the food needs to be hygienically pure. At a subtle level, it means food that is prepared and served by people with good temperament and with affection.

The 24th verse of the 4th chapter of Gita is the Brahma-Yajna-Mantra. It is uttered with a deep sense of reverence before people eat food, so the food is purified. With the imagery of a Vedic ritual (Yajna), this verse says: “the process of offering, what we offer, the one who offers, into what it is offered, the act of performing the ritual, the goal to be reached – everything is Brahman.”

There is nothing in this world, but Brahman. With this strong conviction, when we utter this mantra before eating food, then whatever we eat becomes purified. Whatever we eat, we should eat with a prayerful attitude.

We should be moderate when it comes to eating food. Our body should not complain after we eat food. Extreme fanatical fasting and extreme gluttony are both non-spiritual.
9th verse: “Foods that are bitter, sour, saline, hot, pungent, dry and burning are liked by those endowed with Rajo guna.”

Food that creates temporary emotional excitement, violent tendencies, and disturb the balance of the mind are of the rajasika type.

Gita has no reference to vegetarianism. There is no indication that ancient vedic culture was a vegetarian culture. The discussion of sattvik, rajasik and tamasik food goes beyond the concepts of vegetarian and non-vegetarian. Lord Krishna is addressing food in the context of the entire humanity.