Strength, health, longevity and vital breath are dependent on the state of agni that burns when fed by the fuel of food and drink or dwindles when deprived of them.
The consideration of heaviness and lightness of food articles is particularly important for those who are generally weak, indolent, unhealthy, fragile or in a delicate condition of health, and those given to luxury.
For those whose agni is strong, are accustomed to tough-to-digest food articles, are accustomed to hard labor and have a large capacity for consumption and digestion of food, the consideration of heavy and light food is not necessary.
A person with discipline and self-control should always feed his agni with the fuel of wholesome food and drink and stay mindful of the consideration of measure and time.