Ekadashi is the commonest recurring fast in Hinduism and the rules are more specific than most outsiders expect: the prohibition is on grains and pulses rather than on food as such, so fruit, milk, nuts, potatoes and certain flours are permitted, and an entire cuisine of fasting food exists to fill the gap. It falls twice a lunar month, and the exact window for breaking it, the parana, is calculated astronomically and published, which is why observant households consult a panchanga rather than a wall calendar. Vaishnava traditions treat it as near-obligatory. The historical shadow over it is the treatment of widows, who in orthodox Hindu households were held to a punishing regime that included Ekadashi kept without water, along with a shaved head and a single white garment — a practice reformers campaigned against through the nineteenth century and which persisted in places well into the twentieth.