Segunda Actividad: Definiendo los Poliedros Cóncavos

It is the job of a trained physician to be able to distinguish those patients who are proper candidates for fasting from those who are not. It cannot be assumed that every individual can fast safely for a prolonged period of time—or at all. Occasionally it is necessary to end the fast many days before the patient wants to or the doctor intended to.

A physician should evaluate the patient on a daily basis. He must monitor blood pressure, pulse, and any other parameter that may be appropriate for that individual. Blood tests should be monitored at least weekly to assure adequate electrolyte balance and reserve as well as to check hydration status. With the appearance of sudden weakness or persistent vomiting, additional laboratory work is appropriate to assess electrolytes and hydration status.

Rarely, a patient may be encountered who cannot fast. For instance, some people have an enzyme defect called MCAD (medium-chain acyl-CoA dehydrogenase) deficiency, and it would be unsafe for these individuals to fast. MCAD is one of the enzymes needed for the oxidation of fatty acids. A deficiency in this enzyme is one of the most common inborn errors of metabolism. Since fatty acid oxidation is required as an alternate energy source during fasting, this disorder may go undiagnosed until a person attempts to fast. Even though this condition is exceedingly rare, respiratory failure, extreme weakness, seizures, coma, or death may ensue if the individual continues with a prolonged fast. This disorder is recognized by vomiting or extreme lethargy early in the fast; in addition, the urine does not show ketones as in a normal person who undergoes food deprivation.

Proper supervision also involves a blood test prior to the fast to ensure adequate liver and kidney function. I do not recommend fasting for patients with laboratory findings of significant liver or kidney disease. Extremely weak and debilitated patients generally should not fast. Nor should patients with severe anemia, severe nutritional deficiency states, porphyria, or pregnancy. Patients who are severely malnourished, such as those with advance stages of cancer or AIDS, should not fast because fasting will likely contribute to their malnourished state and perhaps to an earlier death.

Generally, medications should be tapered and discontinued prior to the fast whenever possible. Normally, I taper medication as the patient adopts a healthy diet and postpone the fast until it is safe to discontinue most medication.

Frequently, I encounter patients taking multiple chemotherapeutic agents, such as oral gold and methotrexate, who desire to fast. I do not fast these patients until they can be stabilized with less toxic medication. This is because of my concern that certain drugs when combined with fasting can potentially cause toxic insult to the kidneys. If these patients cannot reduce their dependency on such agents through appropriate dietary and nutritional management prior to the fast, they are not desirable candidates for a fast.

Clearly, a list can be made of hundreds of medications that should not be combined with therapeutic fasting. It would be inappropriate to compile such a list here. Suffice it to say that, except in rare instances, a patient should be stable enough to be able to stop all medication either before a fast or within a few days after the fast has begun, or a fast should not be entertained.

Extreme caution is necessary when fasting a person who has taken oral steroids for a prolonged period in the recent past. Even if the individual has been slowly weaned off the drug well in advance of the fast, adrenal gland suppression is still possible. As a result, fasting could cause an excessive loss of sodium, low blood volume, and rapid heart rate. These parameters should be more closely monitored in such patients. The fast may have to be discontinued at the onset of such signs or symptoms.

In cases in which hormone replacement is essential (for instance, with panhypopituitarism or hypothyroidism), administration of the appropriate hormone(s) may be continued during the fast. However, blood parameters should be observed and the medication dose lowered accordingly, because these patients generally require much less medication during the fast than when eating. Thyroid medication, for example, should be tapered to about one half the patient's usual dose a few days prior to the fast and then periodically monitored with blood tests to ensure the correct dose is being given.

Patients taking drugs such as antidepressants, tranquilizers, or narcotics should not fast. Patients on anticoagulation therapy with Coumadin or chemotherapeutic agents should not fast. Aspirin and other NSAIDs should be discontinued prior to the fast because of the increased risk of gastric irritation during the fast.

Oral hypoglycemics must be discontinued prior to the fast and insulin should be tapered off in the type II diabetic. Type I diabetics should not undergo a prolonged fast.

Since fasting is so effective at lowering blood pressure, hypertensive medication should be stopped prior to or early in the fast. For patients with dangerously high blood pressure who require some medication in the early stages of the fast, a transdermal clonidine patch is usually tolerated well. The

patch is needed only temporarily, until blood pressure decreases to a satisfactory level. Nitrates are compatible with fasting as long as the blood pressure is not too low, and can be continued in patients with angina. Angina, however, invariably resolves with fasting, thereby eliminating the need for nitrates at some point in the fast.