Food is divided into 3 categories satvic, rajasic and tamsic.
Bhagvad Gita 17:8-10
rasyah snigdhah sthira hridya
puti paryushitam ca yat
ucchishtam api camedhyam
Eating foods that are of sattva guna the mode of goodness are pleasurable. Joyfulness is the immediate result. Whatever continues to be pleasurable is joyous to hrdya the heart. Even if all foods are cooked they all do not get digested the same. Ghee and honey are absorbed into the body directly, fruits take an hour to digest and vegetables and grains up to six hours. Some foods although bitter are agreeable to health such as kerala or bitter melon and some foods although sour like yoghurt are agreeable to health if not taken at night. Both of these are of sattva or goodness. Such is the nature of the pious and the saintly and that nature is maintained by the intake of foods that are sattva. The Shabda Niranya states: Hridyam is that which is pleasing to the heart and makes one desire for more. Pleasure is what is pleasing for the moment. Sukham or happiness is that which continues to keep one joyous long after the activity has ended. That food which retains its agreeability even after consuming repeatedly is rasyam which is delicious and nutritious. But when foods are excessively bitter, spicy, salty. sour, pungent, etc. and result in discomfort and misery culminating in sickness and disease they are of raja guna the mode of passion. The food which is eaten more than three hours after it is cooked is known as yatama. When the food is tasteless it is also called yatayama. Food that once was flavourful but later becomes later has no taste is known as gatarasyam. The Suddhasastra states that one devoted to serving the Supreme Lord Krishna or any of His authorised incarnations should thoroughly understand the nature and quality of food.
It is the purest food, the most suitable one for any and everyone . It nourishes the body and maintains it in a peaceful state. And it calms and purifies the mind, enabling it to function at its maximum potential. A Sattvic food thus leads to true health; a peaceful mind in control of a fit body, with a balanced flow of energy between them. It includes: Cereals, wheat, rice, certain fruits and vegetables, milk, butter, legumes, nuts, whole grains, spices, honey. Oils and so on.
They are very hot, bitter, sour, dry or salty. They are tasty only if one develops a taste for them otherwise, they are not palatable. They need to be fried and then treated with spices before they can be served. They destroy the mind-body equilibrium, feeding the body at the expense of the mind. Too much Rajasic food will over-stimulate the body and excite the passions, making the mind restless and uncontrollable. Eating in a hurry is also considered rajasic. It includes: potato*, carrot, cauliflower, raddish, brinjal, beetroot, drumstick, sorekai.
It benefits neither the mind nor the body. Prana (life force) or energy is withdrawn, powers of reasoning become clouded and a sense of inertia sets in. The body’s resistance to disease is destroyed and the mind gets filled with dark emotions, such as anger and greed. Overeating is also considered tamasic. It includes: potato, onions, garlic, fermented foods such as vinegar, stale overripe substances.