From the very beginning of His childhood life Sri Caitanya Mahaprabhu introduced the system of observing a fast on the Ekadasi day. In the Bhakti-sandarbha, by Srila Jiva Goswami, there is a quotation from the Skanda Puran admonishing that a person who eats grains on Ekadasi becomes a murderer of his mother, father, brother and spiritual master, and even if he is elevated to a Vaikuntha planet, he falls down. On Ekadasi, everything is cooked for Vishnu, including regular grains and dhal, but it is enjoined that a Vaisnava should not even take visnu-prasadam on Ekadasi. It is said that a Vaisnava does not accept anything eatable that is not offered to Lord Visnu, but on Ekadasi a Vaisnava should not touch even maha-prasadam offered to Visnu, although such prasadam may be kept for being eaten the next day. It is strictly forbidden for one to accept any kind of grain on Ekadasi, even if it is offered to Lord Visnu. = REF. Adi 15.10 Ekadasi literally means "the eleventh day." There are two Ekadasis in a month : on the eleventh day after the new moon, and on the eleventh day after the full moon. Of all vratas (vows of austerity), Visnu is most pleased with those who observe the Ekadasi vrata. Therefore anyone who does not observe the vrata and eats grains on Ekadasi is said to eat sin, for he disobeys the Lord's order and thus displeases Him. Thus, although Ekadasi fasting is good for health, it should be undertaken principally for the sake of pleasing Krsna. To observe Ekadasi vrata and Dvadasi vrata means to please the Supreme Personality of Godhead. Those interested in advancing in Krsna consciousness must observe Ekadasi regularly.(SB 9.4.29) Hari Bhakti Vilasa quotes from many scriptures to establish the necessity of observing the Ekadasi vrata, to glorify the vrata, to establish the proper day on which to observe the vrata, and to give the proper mode of observance. Observing the Ekadasi vrata (vow of austerity) is one of the principal duties of Vaisnavas. To fail to do so is a serious offence. Bhaktivinoda Thakura has sung, madhava-tithi bhakti-janane jatane palana kari (Suddha-bhakata, from Saranagati): "I observe with great care the holy days like Ekadasi and Janmashtami, for they are the mother of devotion." All people, male and female, of all castes and ages, from eight to eighty, should observe the Ekadasi vrata in all circumstances. This applies to the Ekadasis of both the waxing (gaura or sukla) and waning (krsna paksa) phases of the moon.
All devotees must avoid the following foods on Ekadasi : grains (wheat, rice, etc.), dahl, peas, bean type vegetables, mustard seeds, sesame seeds (except on Sat-tila Ekadasi, when sesame [tila] seeds may be offered and eaten), derivatives of these foods (wheat flour, mustard oil, soya bean oil etc.), and food items containing these products. For instance, care should be taken in using powdered spices, which, if mixed with flour, should not be used on Ekadasi. Particularly, commercially prepared powdered asafatoeda (hing) is always mixed with flour and is not to be used on Ekadasi. If even a slight piece of grain is ingested, even accidentally, the Ekadasi fast is broken. Devotees should not even think of neglecting the Ekadasi fast, unless its observance would severely strain their health. Only in rare cases, those who are physically unable to fast may take grains on Ekadasi, but then only with the explicit permission of their guru. Those who, in the course of the year, break the Ekadasi fast even once, should observe the yearly Bhima Nirjala Ekadasi (see below). Pancaratra Pradipa states: "One who is very strictly observing Ekadasi should avoid all spices except pepper, rock salt and cumin. He should also eschew certain vegetables, such as tomatoes, cauliflower, eggplant, and leafy vegetables." Simpler than this and even more strict is to fast completely. Srila Prabhupada usually observed the Ekadasi fast in the simplest manner prescribed in scripture, by refraining from eating grains, beans, peas and dahl. Sometimes he observed a half-day fast. Some devotees eat only fruit on Ekadasi, some take only water, and some fully fast, even from water (this latter is called nirjala vrata). Non-grain high carbohydrate foods are often prepared on Ekadasi. Sago (tapioca) is a common example. But sago is sometimes mixed with rice flour, and apparently sometimes even with crushed insects. So unless one is sure about the source, sago should be avoided. In India, preparations resembling capatis and rice are made on Ekadasi from non-grain ingredients. Srila Prabhupada was pleased if his disciples strictly observed ekadasi, but he did not emphasize it. (Tamal Krsna Goswami): I told Srila Prabhupada we were strictly observing Ekadasi, no eating or drinking. He said, "Very good." (TKG'S Diary, page 70) Actually on the Ekadasi days we should not take any food, or even drink water. But in our society we are not doing so strictly. We say, "On Ekadsi, you don't take food grains. Take a little fruit, milk." Ekadasi day, there is no eating sumptuously. Simply you take a little fruit and flower. Try to avoid that also. You don't take even water. That is really Ekadasi. But because we cannot do it in the Kali-yuga the time is different therefore we are allowed to take a little fruit and milk, which is called anukalpa. For those who are accustomed to full fasting from a young age and have the physical strength for it, refraining from food and water on Ekadasi is an excellent practice. Not only food, but also sleep is supposed to be given up or minimized on Ekadasi. Those who are so practised may also stay awake all night on Ekadasi, chanting the glories of the Lord. Yet, due to so many discrepancies of modern life, the physical strength of the average person is much less than when this type of fasting was commonly practiced. Therefore many devotees who try to follow this vow become physically devastated. Even if they force themselves to stay awake throughout the night, they cannot properly chant because of hunger, weakness and tiredness. In such cases, is better to follow the process of devotional service according to one's physical ability, rather than attempt something one cannot properly do. Fasting means if you don't feel weak, then you fast--not that you imitate Raghunatha dasa Gosvami. That is not possible in the beginning. But it is possible if you practice. It is not unusual to feel a little weak when fasting, although with practice one can fast without being disturbed by weakness. However, if a devotee feels too weak to properly perform his standard services, it is better that he take a little non-grain prasada on Ekadasi and continue with his regular activities. If there is service and on my fasting, service will be stopped, then I can take. First consideration: service. Now if somebody feels weak, he can take maha-prasada, render service. ( Morning Walk Los Angeles, June 7, 1976) Full fasting on Ekadasi is good for health and good practice in restraining the senses, yet the main purpose of observing Ekadasi-vrata is to increase remembrance of Krsna. One who thinks of food instead of Krsna gets little benefit from fasting. It is therefore better, both for health considerations and to help the mind from being diverted, to break fast with a simple rather than elaborate meal. One of the limbs of a vrata is to diminish the devotee's propensity for enjoyment. If one thinks, "Today somehow or other I will renounce, but tomorrow I will enjoy profusely," then the purpose of the vow will not be successful. If a devotee who is fasting sleeps more due to weakness (real or imagined), cannot rise the next morning, or makes elaborate arrangements to enjoy breaking the fast the next morning, he will derive little benefit. When Tamal Krsna Gosvami asked Srila Prabhupada if devotees could fast fully on Ekadasi, Prabhupada replied "Yes, but don't lie down and sleep." Artificial observance is merely a superficial austerity. Indeed, the disturbance to a devotee's regular routine and service may even be a hindrance to his spiritual advancement. Nor should devotees do strict fasting to impress others, or think themselves superior for doing so, or put pressure on others to also do so. Full Ekadasi fasting is optional, and should not be forced onto anyone.
Observance of Ekadasi vrata is calculated to begin at sunrise. The period before sunrise is considered to be part of the previous day. So the Ekadasi vrata starts at sunrise and lasts until the next sunrise. We observe Ekadasi from sunrise to sunrise. Twelve midnight is the western astronomical calculation, but the Vedic astronomical calculation begins either from the sunrise or the moonrise. Generally it is sunrise. Our calculation is like this: when the sunrise is there, Ekadasi tithi (date) must be there. If the tithi begins a few minutes after the sunrise, then we accept that day as prior to Ekadasi. ( Letter to: Madhudvisa, 30 September, 1969 ) If one eats grains during the period from sunrise to sunrise, one breaks the vrata. He will not get the results of the fasting, and he will get impious reactions as well. In Vedic culture the day begins at sunrise no matter when the lunar tithi begins (The Vedic system differs from the Gregorian calendar in as much as the days are named are deemed to begin at sunrise, rather than midnight). Therefore, technically speaking, since ekadasi or any other day does not begin until sunrise, one could eat grains before sunrise. However, one should generally not eat in the pre-dawn hours, and especially not on ekadasi. Hence, ekadasi fasting and other observances should be followed from the time of waking up on the ekadasi vrata day. Some Vaisnavas are particular not to eat anything after sunset the night before, to make sure there is no undigested food left in the stomach on ekadasi day.
Ekadasi fasting ends with parana, i.e., breaking the fast the next day (Dvadasi) by taking grain prasada. Parana must be performed within a specific time, calculated separately for each Dvadasi. For the dates of Ekadasi and the times for breaking fast, one can consult the Vaisnava calendar (available from ISKCON centers). The specific calendar used by ISKCON should be used, as the prescribed dates for Ekadasi and important festivals may vary according to the system of calculation used by the panditas in each sampradaya. If devotees accidentally break the fast on Ekadasi, they should observe fasting on the following day. Hari Sauri Prabhu recalls an occasion when: The devotees inadvertently broke the Ekadasi vow because the cook accidentally put peas in the vegetable preparations. Srila Prabhupada told us we were all nonsense. He angrily rebuked us, "Now you have to fast for three days!" This shocked everyone. "Yes, that is the procedure," he confirmed. Seeing the stunned look on our faces he relented, but said that we should observe Ekadasi for the rest of the day and then again tomorrow on Dvadasi. ( Transcendental Diary, 1.258 ) Similarly, if the morning fast to be observed on an appearance or disappearance day of an acarya or avatara is inadvertently broken, it should be followed the next day. (c.f. TD4 p.42)
It is said that the Pandava Bhima could not observe fasting on ekadasi and so Krsna told him to fully fast, even from water, only once a year. This comes annually in the month of Trivikrama, at the hottest time of the year in India, which makes it a great austerity to observe. This day is also known as Pandava nirjala ekadasi or simply nirjala ekadasi. Srila Prabhupada did not emphasize strict following of nirjala ekadasi without taking water. Hari Sauri Prabhu recounts that "When I was with Srila Prabhupada in 1976 nirjala ekadasi was observed while we were in America. Prabhupada never mentioned that we should strictly observe it by fasting from water."
For many devotees, Ekadasi simply means a change of diet. Many hardly even notice Ekadasi coming and going. But Ekadsi observance means more than refraining from eating grains. The traditional system of following the Ekadsi vrata is to fast and stay awake all night chanting the Lord's glories. It is a three day austerity that entails taking only one simple meal before nightfall on Dasami (the day before Ekadasi), and a similar simple meal on Dvadasi (the day after Ekadasi). Although this strict observance may not be practicable for most devotees, everyone should try to take advantage of the auspicious time of Ekadasi to advance in Krsna consciousness. In the Brahma-vaivarta Purana it is said that one who observes fasting on Ekadasi day is freed from all kinds of reactions to sinful activities and advances in pious life. The basic principle is not just to fast, but to increase one's faith and love for Govinda, or Krishna. The real reason for observing fasting on Ekadasi is to minimize the demands of the body and to engage our time in the service of the Lord by chanting or performing similar service. The best thing to do on fasting days is to remember the pastimes of Govinda and to hear His holy name constantly. ( NOD Ch.7 ) Srila Prabhupada recommended that devotees with sufficient time chant twenty five or more rounds of japa on Ekadasi. Why just twenty-five rounds? You should chant as many as possible. Real Ekadasi means fasting and chanting and no other business. When one observes fasting, the chanting becomes easier. So on Ekadasi other business can be suspended as far as possible, unless there is some urgent business. ( Letter to: Jadurani, 9 July, 1971 ) However, although Srila Prabhupada told a few devotees to chant twenty-five rounds on Ekadasi, he did not make it compulsory for all. He particularly exempted devotees busy in preaching from the necessity to chant extra rounds. Tamala Krishna: We should always chant twenty-five rounds on ekadasi if initiated. Prabhupada: Initiated? Everyone. Why initiated? Tamala Krishna: So that should be standard for our movement on ekadasi day? Prabhupada: Standard is sixteen, but if one can chant more, then he is welcome. Tamala Krishna: It's not mandatory for ekadasi. Jayapataka : Recommended. Prabhupada: No. Ekadasi means that, fasting and chanting. Tamala Krishna: Sometimes I'm wondering, because our men have to go out on book distribution. Prabhupada: No, no. That is also preaching work. For that purpose you can stop this, but generally, one who has no preaching work, he can chant extra. And even preachers sometimes need to wind down and get recharged with an extra dose of hearing and chanting, for which enhanced Ekadasi performance provides the ideal opportunity.