The Spiritual Exercises of St. Ignatius of Loyola, , at sacred-texts.com
Second Rule. The second: Abstinence appears more convenient as to drinking, than as to eating bread. So, one ought to look much what is helpful to him, in order to admit it, and what does him harm, in order to discard it.
Third Rule. The third: As to foods, one ought to have the greatest and most entire abstinence, because as the appetite is more ready to act inordinately, so temptation is more ready in making trial, on this head. And so abstinence in foods, to avoid disorder, can be kept in two ways, one by accustoming oneself to eat coarse foods; the other, if one takes delicate foods, by taking them in small quantity.
Fourth Rule. The fourth: Guarding against falling into sickness, the more a man leaves off from what is suitable, the more quickly he will reach the mean which he ought to keep in his eating and drinking; for two reasons: the first, because by so helping and disposing himself, he will many times experience more the interior knowledge, consolations and Divine inspirations to show him the mean which is proper for him; the second, because if the person sees himself in such abstinence not with so great corporal strength or disposition for the Spiritual Exercises, he will easily come to judge what is more suitable to his bodily support.
Fifth Rule. The fifth: While the person is eating, let him consider as if he saw Christ our Lord eating with His Apostles, and how He drinks and how He looks and how He speaks; and let him see to imitating Him. So that the principal part of the intellect shall occupy itself in the consideration of Christ our Lord, and the lesser part in the support of the body; because in this way he will get greater system and order as to how he ought to behave and manage himself.
Sixth Rule. The sixth: Another time, while he is eating, he can take another consideration, either on the life of Saints, or on some pious Contemplation, or on some spiritual affair which he has to do, because, being intent on such thing, he will take less delight and feeling in the corporal food.
Seventh Rule. The seventh: Above all, let him guard against all his soul being intent on what he is eating, and in eating let him not go hurriedly, through appetite, but be master of himself, as well in the manner of eating as in the quantity which he eats.
Eighth Rule. The eighth: To avoid disorder, it is very helpful, after dinner or after supper, or at another hour when one feels no appetite for eating, to decide with oneself for the coming dinner or supper, and so on, each day, the quantity which it is suitable that he should eat. Beyond this let him not go because of any appetite or temptation, but rather, in order to conquer more all inordinate appetite and temptation of the enemy, if he is tempted to eat more, let him eat less.