What Is Starvation?
Contrary to what many people believe, fasting is not starvation. Starvation begins when abstinence is continued beyond the time when the body’s stored reserves are used up or have dropped to a dangerously low level. During the fasting stage the body supports itself from the stored reserves within its tissues. When food is eaten at normal intervals, the body stores sufficient amounts of nutritive matter to last for a rather lengthy time during later periods of abstinence. Even thin people carry a reserve of nutrients in their tissues to tide them safely over a period of fasting.
The body will not starve or in general even be hungry while fasting because it is “eating.” It is consuming the substances the individual consumed last week, last month, and last year that have been converted into body tissue. In fact, the symptoms of hunger generally disappear by the second day of the fast. This illustrates that the body has entered a fasting, and (lean) tissue-sparing metabolism. Of course, there is a limit to the body’s reserves. When they have been used up, specific symptoms occur that indicate the fast should not be continued.
The time required for a fast to reach completion varies from individual to individual. The trained physician can easily denote symptoms that indicate the ending of the fasting period and the beginning of starvation. In the vast majority of fasts, the physician will end the fast many weeks before the nutrient reserves of the body have been exhausted. The average individual (not overweight) would have to fast approximately 40 days or more to exhaust nutrient reserves. Such a prolonged fast is almost never recommended and, therefore, we are not remotely considering the biologic processes of starvation during the fast of average length. If the fast was continued beyond the point when the body’s nutrient reserves were exhausted, starvation would begin. If not eating was continued past this point, damage to the body and even death could result. Most patients are fasted one to four weeks depending on their nutritive reserves and the purpose of the fast.