The Usual Limit of Abstinence and of Eating

But this is the usual limit of abstinence: that each person allows himself food according to what his strength, his bodily build, or his age requires, in the amount needed to support the flesh, and not to give a satisfying feeling of fullness. For a man will suffer the greatest harm either way if, having no fixed rule, he at one time pinches his stomach with meager food and fasts, and at another stuffs it by overeating. For just as the mind weakened by lack of food loses its vigor in prayer, worn out by excessive weakness of the flesh and forced to doze, so again, when it is weighed down by overeating, it cannot pour out pure and free prayers to God. Nor will it succeed in keeping the purity of its chastity unbroken, since even on the days when it seems to discipline the flesh with stricter abstinence, it is feeding the fire of fleshly desire with the fuel of the food it has already taken.