The first temptation that our Lord undergoes in the desert is one that is directly occasioned by his fasting. It is the hunger of the fast that opens him up to temptation:
And he fasted forty days and forty nights, and after that he was hungry. And coming up to him the tempter said: If you are the son of God, speak and make these stones become loaves of bread. But he answered, saying: It is written: not by bread alone shall man live, but in every word that issues through the mouth of God.Matthew 4:2-4
A comment on James Chastek’s blog a while back noted the following about the effects of fasting for several weeks on water only:
Fasting of this type is characterized by phases involving the presence, absence and then return of hunger, with the final hunger being quite different both subjectively and in its objectively imperative nature from the initial hunger phase, which is like what most people think of, and experience as, hunger.
When one embarks on an extended water fast, one transitions into it with feelings of pangs in the stomach, cravings for food, lassitude. This can last for several days up to a week. After a while, the real fast begins: hunger pangs disappear, energy levels may rise, the body begins living on its fat stores, the tongue may become coated, the breath foul, and sometimes skin eruptions appear as toxic deposits are excreted through it as a byproduct of metabolism. The key here, which often surprises people, is the absence of hunger.
Then–and here’s the relevance to Jesus and the forty days–after several weeks, hunger returns. But it is radically different than the initial hunger, which is the hunger you and I think of as hunger. The tongue becomes clear, the breath freshens, the skin ceases to break out. The body has used up its fat stores, and now signals its need for nutriments with the return of hunger. But this hunger is different: it is not experienced as hunger pangs, but as a deep need throughout the body, a kind of cellular craving for food. It is not exactly unpleasant (at first: after any delay in eating, it becomes agony), but it is imperative, and it must be honored. Because now the faster is in genuine starvation. “And he was hungry.”
A typical time from onset of food elimination to return of imperative hunger: oddly, about forty days is not unusual. Some can go quite a bit longer, some quite a bit less. But a typical adult man with typical stores of fat can go about five or six weeks. But when that time is up…you MUST eat. Your body craves food desperately. You must eat, or you will begin to die.
This account is bolstered by what we read of cities under siege in ancient accounts. There comes a time when the inhabitants of a starving city seem to lose the use of reason—everything else becomes secondary in comparison to hunger. Parents even eat their own children. Even that most natural of all loves is clouded over by this craving in every cell of the body. Such cannibalism is a drastic illustration of Abraham Maslow’s famous “hierarchy of needs;” if you physiological needs are not met, one will not worry about higher goals. Or, as Bertolt Brecht put it more pithily: First comes grub, then morality.
But in rejecting the temptation, Christ rejects the whole idea of ranking what is more necessary above what is more good:
Do not then worry and say: What shall we eat? Or: What shall we drink? Or: What shall we wear? For all this the Gentiles study. Your father in heaven knows that you need all these things. But seek out first his kingdom and his justice, and all these things shall be given to you.Matthew 6:31-33