Mr. Faill: Is it necessary to follow certain eating habits to practice spiritual life?
Śrīla Prabhupāda: Yes, the whole process is meant to purify us, and eating is part of that purification. I think you have a saying, “You are what you eat,” and that’s a fact. Our bodily constitution and mental atmosphere are determined according to how and what we eat. Therefore the śāstras [scriptures] recommend that to become Kṛṣṇa conscious, you should eat remnants of food left by Kṛṣṇa [kṛṣṇa-prasādam]. If a tuberculosis patient eats something and you eat the remnants, you will be infected with tuberculosis. Similarly, if you eat kṛṣṇa-prasādam, then you will be infected with Kṛṣṇa consciousness. Thus our process is that we don’t eat anything immediately. First we offer the food to Kṛṣṇa, then we eat it. This helps us advance in Kṛṣṇa consciousness.
Mr. Faill: You are all vegetarians?
Śrīla Prabhupāda: Yes, because Kṛṣṇa is a vegetarian. Kṛṣṇa can eat anything because He is God, but in the Bhagavad-gītā [9.26] He says, “If one offers Me with love and devotion a leaf, a flower, a fruit, or water, I will accept it.” He never says, “Give Me meat and wine.”
Science of Self-Realization (p. 185)
Source: The Higher Taste – BBT