Ayambil is a Jain form of fasting in which the observer eats only a single bland, boiled meal a day, taken without any of the six "tastes" or enriching substances, no oil, ghee, milk, curd, sugar, salt beyond the minimal, green vegetables or fruit, so that the food is deliberately plain and unappetising. The purpose is the disciplining of the palate and, through it, of desire: by reducing eating to bare sustenance stripped of pleasure, the practitioner curbs the attachment to taste that Jain teaching regards as one of the bonds of the senses, and turns the mind toward austerity and reflection. Unlike a complete fast, ayambil sustains the body enough to allow continued religious activity while removing from food nearly everything that makes it a source of gratification.
The practice is most fully expressed in the Ayambil Oli, twin nine-day periods observed twice a year in spring and autumn, during which the devout take only the ayambil meal each day and give the time to worship, the veneration of the qualities of the enlightened beings, and study. Ayambil embodies the characteristic Jain understanding of austerity, tapas, as the deliberate acceptance of hardship in order to shed karma and advance the soul, and it illustrates the tradition's fine gradation of ascetic practice, in which many forms of restraint short of a total fast are cultivated as steps in the lifelong discipline of detachment.