Śrīla Bhakti Rakṣak Śrīdhar Dev-Goswāmī Mahārāj explains how fasting should be observed on Śrī Ekādaśī.
Śrīla Śrīdhar Mahārāj: Will you take some anukalpa?
Śrīla Śrīdhar Mahārāj: As you like.
Student: No, as you like.
Śrīla Śrīdhar Mahārāj: You see, service is better than sitting idle. So, prasād-sevā, if it is service, if it is done in a serving mood of course. At the same time, the individual position of a devotee should be taken into consideration. The sahajiyās do not observe Ekādaśī fasting at all: “Oh! We are in Vṛndāvan. No fasting here!” Śrīla Bhakti Vinod Ṭhākur and Śrīla Prabhupād did not like that everyone will go on feeding the senses in the name devotion to Kṛṣṇa. But when it is necessary for the service of Kṛṣṇa to nourish the body, then we don’t like that by taking to fasting a loss of energy may be affected. In this way we are to honour Ekādaśī. But if fasting does not hamper your service, then you may go on fasting.
Student: Is having a diet of fruit and milk considered fasting?
Śrīla Śrīdhar Mahārāj: Without any water, that is first-class fasting. Then, there is a mixed fasting, and one who cannot do that can take all these things. There is a gradation. One who cannot do without anything can take water. Then, one can take fruit juice. Then one can take underground roots, potatoes and so. Then milk, in this way. Lastly after sunset, one can take haviṣyānna, a little plain rice. But on Ekādaśī, sin takes shelter in grains, so rice must be left. Fruits, roots, and milk may be taken for the purpose of service. We take anukalpa. The ruling is there that service is first; service must be given higher consideration. Why? If I fast and do not take any water, I will lie down and not be able to do any service to the Lord. That is not desirable. So, we take anukalpa and do service to the Lord. That will be better.
Spoken on 3 March 1981 and 31 August 1982.