Both Ayurveda & Yoga traditions teach that the food is not only for nutrition or to nourish the physical body but it also influences the mind & consciousness.
As we have a physical constitution (vata, pitta, kapha), we also have mental constitution characterized by the three Gunas (called sattva, rajas, tamas).
According to Sankhya philosophy; sattva, rajas & tamas are the three universal qualities necessary for the creation of the universe.
All are equally important to maintain our psychobilogical functions:
Because of Sattva we remain conscious and reawaken every morning.
Because of Rajas our thoughts, feelings and emotions move in a creative way.
Because of Tamas we become tired, exhausted and heavy. Without Tamas there is no sleep possible.
These three qualities are also necessary for the functioning of every cell. Sattva is considered potential energy, rajas is kinetic energy & tamas is inertia.
The potential energy in the cell is awareness, it becomes active due to the kinetic energy of rajas, then the cell becomes inert due to the quality of tamas. For common people, all three are necessary to find the balance in materialistic world.
But to uplift yourself from the level of common human being, Yoga tradition highly emphasized to develop the quality of Sattva to get freedom from the boundages & sufferings.
There may be many ways to acquire the Sattva quality (guna); like different spiritual practices, yogic practices,... etc, out of those, one is Ahara (food).
Bhagavad Gita explains three types of food in chapter 17th. Let us see:
Bhagavad Gita 17/8:
Ayuh- sattva-balarogya sukha-priti-vivardhanah |
Rasyah sniggdhah sthira hrdya aharah sattvika- priyah ||
"Foods dear to those in the mode of goodness increases the duration of life (longevity), purify one's existence and provides the strength, health happiness and satisfaction. Such foods are juicy, fatty, wholesome and pleasing to the heart."
Sattvic diet consists of pure food (not processed) that is light in digestion & rich in prana (life force, energy). It energizes the body & relaxes the mind. It induces sense of refreshment, satisfaction & peace.
Hatha yoga pradipika 1/59:
"Food that is well lubricated, sweet, leaving one fourth part of capacity, consumed for pleasure of God in side is said to be balanced diet."
Another shloka - 1/62.
"Food items that are considered to be conducive for a yoga practitioner are: wheat, rice, barley, good grains like a variety of rice crop grown in sixty days, cow milk, ghee, jaggery, butter, sugar, honey, dry ginger, cucumber, seasonal fruits etc..., five leafy vegetables, greengram lentil etc..."
Note: here sugar doesn't mean white sugar.
Another one more, see the shloka 1/63:
"A yogi should consume the food that is contributing to health; sweet, lubricated, made of cow milk, nourishing to the fundamental element of the body (called Dhatus), agreeable to one's own mind or taste and which is conducive and fulfilling all conditions (of Yogic food)."
Sattvic diet can not be measured/calculated by one parameter.
There are many parameters of it.
For example: someone takes the pumpkin cooked vegetable with barley chapati (breads). Both are sattvic in nature but if the food is overtaken compared to the hunger, or the mood is in state of anger, lust, jealousy...etc then the food can not give the sattvic effects.
So, there are some rules and disciplines we need to observe while cooking & eating.
Remember some points in whole process:
Check the nature of the fruits, vegetables, grains, seeds... are they fresh or old, stored/preserve in cold storages, etc...
The method of cooking: slow fire or high fire; boiling, roasting or frying; cooking in sunlight or without sunlight; the pots used while cooking or during the cooking...
The mood while cooking.
Combinations of different fruits, vegetables, oils, seeds...
The quantity of different ingredients of food.
The time of taking the meal: morning, evening or night.
The season: same food can not give you the same energy for the all 12 months.
Bhagavad Gita 17/9:
Katv- amla-lavanaty-usna- tiksna-ruksna-vidahinah |
Ahara rajasasyeesta duhkha-sokamaya-pradah ||
"Foods that are too bitter, too sour, salty, hot, pungent, dry and burning are dear to those in the mode of passion. Such Foods cause distress, misery and disease."
Bhagavad Gita 17/10:
Yata-yamam gata-rasam puti paryusitam cha yat |
Ucchistam api camedhyam bhojnam tamasa-priyam ||
"Food prepared more than three hours before being eaten, food that is tasteless, decomposed and putrid, and food consisting of remnants and untouchable things is dear to those in the mode of darkness (tamas)."