But her innocence left her a very long time ago, and she never noticed. She eats only grass, but she has a meat eater’s heart.

—Tove Jansson, The True Deceiver

All this is contrary to nature, for the Creator has ordained the same natural way of life for both us and the animals. ‘Behold,’ says God to man, ‘I have given you every herb of the field, to serve as food for you and for the beasts’ (cf. Gen, 1:29-30). Thus we have been given a common diet with the animals; but if we use our powers of invention to turn this into something extravagant, shall we not rightly be judged more unintelligent than they? The animals remain within the boundaries of nature, not altering in any way what God has ordained; but we, who have been honored with the power of intelligence, have completely abandoned His original ordinance. Do animals demand a luxury diet? What chefs and pastry-cooks pander to their bellies? Do they not prefer the original simplicity, eating the herbs of the field, content with whatever is at hand, drinking water from springs – and this only infrequently?

Since, then, possessions are the cause of great harm and, like a source of disease, they give rise to all the passions, we must eliminate this cause if we are really concerned for the well-being of our souls. Let us cure the passion of avarice through voluntary poverty. By embracing solitude let us avoid meeting those who do us no good, for the company of frivolous people is harmful and undermines our state of peace. Just as those who live in an unhealthy climate are generally ill, so those who spend their time with worthless men share in their vices. 

—St. Neilos The Ascetic
Philokalia

And concerning this matter the learning of physicians also testifieth, and they, that is to say their learning, or art, which hath been discovered for the stablishing of the body, know better than all other arts, that the health and sickness of the body arise from the food, [p. 377] and if they be asked, they will always advise sparingness in the use of meat, and in |360 addition to this also they will advise that the food of a man should be meagre, and that he should guard against drinking wine freely. And if they allow a man to drink wine for need’s sake they break the strength thereof with much water, and then give it to him to drink. And they command a man very fully to beware of idleness, and to love fatigue, and to seek work, and with exercises of all kinds which are akin to work they preserve the health of the bodies of the children of men. And these they advise “That the ducts of the body may not be filled with the living liquid which ariseth from the over-eating of meat, and that they may not be blocked up and prevent the passage through them of the living power of the food, which is the strengthener of the body.” And this [passage] also is written in their works: “Meat is the cause of all the diseases of the body, and though by chance they may be produced from other causes, if thou increasest [the use of] meat it becometh a nurse unto them, and preventeth wholly the benefits of the art of the physician.”

—Philoxenus, Ascetic Discourses (1894) pp.337-402. Discourse 10 — On Gluttony

And because they were not refined in their bodies, but in their souls, they chose vegetable food that their bodies might become meagre, and the strength and the natural power of their members might be reduced, and that after these things the living parts of the soul might be revealed unto the perception and sight of divine knowledge. And this actually took place, for after they had eaten pulse and drunk water for three years this knowledge was revealed unto them, not that which is born of words, but that which is born of deeds, for they were doing the works which gave birth unto the knowledge of the spirit, while they were learning the words which gave birth unto human knowledge; but because their expectation was directed unto the revelation of that knowledge which ariseth from works and not unto that which ariseth from words, where they looked they saw, and where they expected they received, and they became a medium for words, and receptive vessels of the knowledge of the spirit. 

—Philoxenus, Ascetic Discourses (1894) pp.403-471. Discourse 11 — On Abstinence

Now Paul crieth unto us, “Let not your hearts be made heavy through the eating of flesh and the drinking of wine”, that he may teach us that meat maketh heavy the heart, but they ate and did not become heavy, and they ate, moreover, that they might show that their lightness was more powerful than the heaviness of meat, and that by that thing which maketh dense the heart their mind became the brighter, and that by that which maketh heavy the body, and darkeneth the mind, the lightness of their understanding became more luminous. For being abstinent, that they should be clean, and pure, and holy, was not accounted by them so great a thing as that they should be purified in the matter of the things which make gross the heart, that is to say, that they should be purified in the matter of the things which are the contrary of purity, that they might overcome like mighty men that which was opposed to them, and that, like men of power and freemen, they might be uninjured by the things which cause injury.

—Philoxenus, Ascetic Discourses (1894) pp.403-471. Discourse 11 — On Abstinence

For from these things we go on to others, and we are lifted up from this step unto others which are higher, and by reason of resisting meats we arrive at the similitude of angels; for inasmuch as the angels exist wholly and entirely without meat, we must of our own free will make ourselves alien unto the meat which is lusted after, and diminish a few of the wants of the body. And by this also we shew that we have in us the longing to be like unto spiritual beings. 

—Philoxenus, Ascetic Discourses (1894) pp.403-471. Discourse 11 — On Abstinence

She abstained absolutely from anything with blood and life in it, but taking fish and vegetables with oil on feast days, at other times she continued to content herself with a mixture of sour wine and dry bread.

—Palladius, The Lausiac History 
CHAPTER LVII.  — CANDIDA

From his private money and from (the produce of) his own labours he bought in Alexandria all kinds of drugs and things needed for the cells, and provided all the brotherhood with them in their illnesses. [2] And one might see him from early morn until the ninth hour going the round of the monasteries and entering in at each door in case there should be any one ill in bed, taking with him dried grapes, pomegranates, eggs, and bread made of fine flour, the things which such people need.

—Palladius, The Lausiac History
CHAPTER XIII.  — APOLLONIUS

For example, in a letter to Marcus Aurelius, we find his rhetoric tutor and family friend, Marcus Cornelius Fronto, joking about how he saw one of the emperor’s little sons clutching a chunk of brown bread, “quite in keeping with a philosopher’s son.” In another letter, we get a glimpse of Marcus’ eating habits:

Then we went to luncheon. What do you think I ate? A wee bit of bread, though I saw others devouring beans, onions, and herrings full of roe.

How to Eat Like a Stoic