Man is essentially what he eats, is an adage that is popular in modern times. Āyurveda, an ancient science, attests to this fact. According to this science, man’s eating habits play an integral role in his mental make-up as well as his physical well-being. The basic tenet of Āyurveda states that health (svāsthya) is a state of equilibrium of three planes – the physical (and physiological,) the mental, and the spiritual. An aberration (doṣa) in any one of the planes results in ailments. The equilibrium is said to be maintained by the three pillars of healthy eating, sound sleep, and regulated sex.
Āyurvedic texts elaborate in detail, the concept of healthy eating. The most interesting arguments on food revolve around the psychological effects of food on man. Āyurveda states that certain foods result in a contented state of mind, certain foods are excitatory, while certain other foods result in lethargy. In accordance with the psychological responses a particular food engenders, that food is categorized as sātvik (calming,) rājasic (excitatory,) or tāmasic (causing lethargy.)
A diet is chosen keeping in mind the constitution (prakṛti) of the person in question, as well as the tasks he/she intends to fulfill. If for instance, a person intends a yogic life, he/she must adhere to a sātvik diet, a diet that is comprised of foods that have a calming effect. This diet may include vegetables, fruits, tubers, nuts and honey, while eschewing extremely bitter, pungent or sour foods. Svātmārāma allocates a separate chapter to yogic diet in his work, Haṭhayoga Pradīpikā. He states,
मिताहारं विना यस्तु योगारम्भं तु कारयेत्।
नानारोगो भवेत्तस्य किञ्चिद्योगो न सिध्यति॥
mitāhāraṃ vinā yastu yogārambhaṃ tu kārayet।
nānārogo bhavettasya kiñcidyogo na sidhyati॥
One who practices Yoga without adhering to a regulated diet invites hordes of ailments and never attains the fruit of Yoga.