The Rule of St Benedict, Chapter 39

“For the daily meals, whether at noon or in mid afternoon, it is enough, we believe, to provide all tables with two kinds of cooked food  because of individual weaknesses. In this way, the person who may not be able to eat one kind of food may partake of the other. Two kinds of cooked food, therefore, should suffice for all the brothers, and if fruit or fresh vegetables are available, a third dish may also be added. A generous pound of bread is enough for a day whether for only one meal or for both dinner and supper. In the latter case the cellarer will set aside one third of this pound and give it to the brothers at supper.

Should it happen that the work is heavier than usual, the abbot may decide – and he will have the authority – to grant some additional provided that it is appropriate, and that above all overindulgence is avoided, lest a monk experience indigestion. For nothing is so inconsistent with the life of any Christian as overindulgence. Our Lord says:Take care that your hearts are not weighed down with overindulgence (Luke 21:34).

Young boys should not receive the same amount as their elders, but less, since in all matters frugality is the  rule. Let everyone, except the sick who are very weak, abstain entirely from eating the meat of four-footed animals.”

We can take from this – don’t overeat but carb load if you’re going to be doing heavy work, lay off the red meat and eat fresh fruit and vegetables. Healthy eating is nothing new.