Gunas

The three gunas — sattva, rajas, and tamas — are, in Samkhya and Vedanta cosmology, the three fundamental qualities of all manifest matter and mind. Every substance, every food, every mental state, every time of day, and every environment is held to be a composition of the three in varying proportion.

A note on the word rajas: in the guna system, rajas names the principle of activity and agitation. The same Sanskrit word is used in Ayurvedic physiology to name the female reproductive essence, where it has nothing to do with the guna and everything to do with the female counterpart to shukra. The two senses share a word but not a meaning. This site writes "rajas" by default for the reproductive essence (see rajas) and "rajas-guna" when the guna is meant.

The three

• Sattva — purity, clarity, harmony, light, knowledge. Conducive to meditation, conservation, and the upward refinement of energy. Cultivated by the discipline.
• Rajas-guna — activity, passion, agitation, motion. Drives outward expression and consumption. Conducive to ordinary worldly engagement but obstructive to deep cultivation when chronically dominant.
• Tamas — inertia, heaviness, dullness, decay. Conducive to sleep and rest but obstructive to function when chronically dominant.

In dietary application

The classical sources classify foods along this axis:

• Sattvic — fresh fruits and vegetables (especially root vegetables and leafy greens), whole grains, ghee (the most sattvic food in Ayurveda), nuts, honey, clean water. The diet of the cultivator.
• Rajasic — heavily spiced foods, onions, garlic, overly salty foods, coffee and strong tea, red meat. Stimulating, encouraging outward expression.
• Tamasic — stale food, heavily processed food, alcohol, any food consumed in excess. Stupefying, encouraging heaviness.

Primary sources

• Bhagavad Gita, chapter XIV — the canonical treatment of the three gunas
• Samkhya Karika — the foundational text of the Samkhya school where the guna doctrine is systematically developed
• Charaka Samhita — the dietary classification

In motion

• See women / the depletion system for the practical application: every condition the cultivation discipline requires is a condition for sustained sattva-dominance, and every condition the modern career structure imposes pushes the body toward chronic rajas-guna activation.
• The Taoist tradition reaches similar conclusions through the Three Treasures framework: Jing as the dense substrate, Qi as the active circulating breath, Shen as the refined spirit.