Holy Rule Of Saint Benedict CHAPTER XXXIX Of the Quantity of Food

Making allowance for the infirmities of different persons, we believe that for the daily meal, both at the sixth and the ninth hour, two kinds of cooked food are sufficient at all meals; so that he who perchance cannot eat of one, may make his meal of the other. Let two kinds of cooked food, therefore, be sufficient for all the brethren. And if there be fruit or fresh vegetables, a third may be added. Let a pound of bread be sufficient for the day, whether there be only one meal or both dinner and supper. If they are to eat supper, let a third part of the pound be reserved by the Cellarer and be given at supper.

If, however, the work hath been especially hard, it is left to the discretion and power of the Abbot to add something, if he think fit, barring above all things every excess, that a monk be not overtaken by indigestion. For nothing is so contrary to Christians as excess, as our Lord saith: "See that your hearts be not overcharged with surfeiting" (Lk 21:34).

Let the same quantity of food, however, not be served out to young children but less than to older ones, observing measure in all things.

But let all except the very weak and the sick abstain altogether from eating the flesh of four-footed animals.