Keep the body properly slim so that you reduce the burden of the heart’s warfare, with full benefit to yourself.

—St Philotheos of Sinai

He ate only bread and salt, and even that not every day.

A Discourse on Abba Philimon
Philokalia

Break the bonds of your friendship for the body and give it only what is absolutely necessary. 

—St. Thalassios the Libyan

Cited alongside these results are estimated calculations of the caloric sum of St. John Cassian’s suggested diet for monks, which amounted to approximately 930 calories daily.

Fasting Reconsidered: St. John Chrysostom and Modern Science on Fasting
Stephen M. Meawad, Ph.D.

Being a King, David had opportunities for temporary pleasures, but after he tasted the sweetness of inner blessings, he even forgot to eat his bread.

—Hieromonk Makarius of Optina

What I eventually found out was that as soon as I started to fast and deny myself pleasures and devote time to prayer and meditation and to the various exercises that belong to the religious life, I quickly got over all my bad health, and became sound and strong and immensely happy.

—Thomas Merton, The Seven Storey Mountain

It is because we did not fast that we were banished from paradise. So let us fast that we may return to it.

—St. Basil the Great

“In the same way, be firm in your fasting. If you are tolerant in the time of abstaining, you will also be tolerant in the type and amount of food, then you will be tolerant in controlling yourself. This lack of control will accompany you in all the details of your spiritual life.”

—H.H. Pope Shenouda III, The Life of Repentance and Purity,

“As quickly as the pleasure of eating and drinking passes away in those sitting at table dining, for instance, so quickly shall pass, and passes away the present life, with all its pleasures, joys, sorrows, and sickness.”

—St. John of Kronstadt