The Chāndogya Upaniṣad presents a detailed analysis of food by classifying it into three types—solid, liquid, and heated (such as oils). Each of these is further divided into three aspects: gross, intermediate, and subtle.

In the case of solid food, the gross portion is excreted, the intermediate portion nourishes the physical body as flesh, and the subtle portion contributes to the nourishment of the mind. This is a clear indication that the mind is directly influenced by what one eats.

Similarly, for liquids, the gross portion is eliminated, the intermediate portion becomes blood, and the subtle portion supports prāṇa. In the case of heated substances like oils, the gross portion contributes to bone, the intermediate portion to marrow, and the subtle portion to the quality of speech.

Modern science, in its own way, also points towards this connection. There is increasing evidence of the relationship between the digestive system and emotional states. For example, variations in stomach pH levels have been linked to emotions such as anxiety or calmness. The communication between the brain and the gut—through mechanisms such as the vagus nerve—further reinforces the understanding that food and mental states are closely related.

Regarding the quantity of food, moderation is emphasised.

In the Bhagavad Gītā, while discussing meditation, Lord Kṛṣṇa advises that neither excessive eating nor excessive fasting is conducive. A balanced approach is essential for maintaining a mind fit for contemplation.

Traditional guidance further elaborates this by suggesting that one’s stomach be divided into four parts—two parts filled with solid food, one part with water, and one part left empty to allow proper digestion.

The Mahābhārata also indicates that eating only at appropriate times, without constant indulgence, is beneficial—an idea that finds resonance with modern practices such as intermittent fasting.

Another traditional teaching advises that food should be regarded as medicine to address hunger. Craving for taste, like any other craving, can become a source of dependence. Therefore, food is ideally consumed to meet biological needs rather than for indulgence.

While enjoying good food is not prohibited, excessive identification with it—such as taking pride in being a “food enthusiast”—is not helpful for a spiritual aspirant.

The Bhagavad Gītā also classifies food based on its effect on the individual.

Food that promotes longevity, clarity of mind, strength, health, and well-being—while being pleasant, nourishing, and balanced—is preferred by those with a sāttvika disposition.

Food that is excessively bitter, sour, salty, hot, or pungent, and that leads to discomfort or disturbance, is associated with rājasic tendencies.

Food that is stale, improperly prepared, lacking in freshness or purity, or unfit for offering, is associated with tāmasictendencies.

These qualities of sattva, rajas, and tamas are also reflected in the mind.

Sattva expresses as clarity, contentment, compassion, balance, truthfulness, and inner strength. It is marked by qualities such as joy, faith, generosity, and calmness.

Rajas manifests as restlessness, ambition, pride, agitation, and emotional turbulence. It includes tendencies such as competition, anger, insecurity, and excessive desire.

Tamas expresses as dullness, confusion, lethargy, carelessness, and lack of discernment. It includes tendencies such as inertia, indulgence, and disregard for values.

Thus, the kind of food one consumes has a direct influence on the state of one’s mind.

Recognising this connection allows one to make conscious choices, aligning one’s food habits with the kind of mental state one wishes to cultivate.