Upvas, or upavasa, is the Hindu practice of religious fasting, a voluntary abstention from food, whole or partial, undertaken as an act of devotion, self-discipline and purification. The Sanskrit term carries a meaning deeper than mere abstinence: it denotes a "dwelling near" the divine, so that the fast is understood not simply as going without food but as drawing close to God by turning the appetites and attention away from the body and toward the sacred. Fasting is woven throughout Hindu religious life, attached to particular days of the week sacred to particular deities, to the fortnightly Ekadashi, to festivals, to vows undertaken for a specific end, and to acts of penance, and its forms range from a complete fast to the taking of a single meal, the avoidance of grains, or a diet of fruit and milk.
The tradition understands the fast to work on several levels at once. It disciplines the body and trains the will against the pull of desire; it is held to purify and to generate spiritual merit; and it concentrates the mind, freed for a time from the demands of eating, upon worship and devotion. Fasting is very often bound up with the keeping of a vow, the vrata, in which the abstention is offered to a deity in petition or thanksgiving, and it is broken at a prescribed time with prayer. As in many traditions, the outward act of going without food is treated as valuable only insofar as it serves this inner turning, and the texts warn against a fasting that is merely of the body while the mind remains fixed on food and on the world.