Contraindications to Extended (beyond 48 hours) Fasting
- Emaciation. Anyone who is severely underweight, for any reason should not fast for long periods. However controlled short fasts can assist in normalising reasons for the emaciation in some cases (malabsorption problems for example).
If emaciation is due to advanced cancer, TB or AIDS or to an eating disorder such as anorexia, then fasting of any sort should not be undertaken.
- Fasting during pregnancy. There exists danger to the foetus in some instances - especially if the woman is also diabetic. Any fasting of a pregnant woman should be under strictly controlled and supervised conditions and for a clearly defined reason. Fasting is contraindicated when breast feeding since milk flow is likely to cease and will be difficult to start again.
- Type l diabetics should not be fasted according to many experts, however some allow fasting as long as glucose levels are tested frequently and insulin intake adjusted according to lowered needs during a fast. Type ll diabetics should also be checked regularly, and they will probably find that sugar levels are normalised during the fast.
- Infants should not be fasted for longer than two days, and they seldom need even that length to respond well to this method of health promotion. There is seldom any reason for avoiding a short fast (36 to 48 hours) in a child of any age, should this be indicated (infection, digestive upset, skin reaction, etc.)
- Kidney failure is thought to be a sound reason for avoiding fasting since the process makes excessive demands on remaining kidney function. However under controlled conditions short fasts can be helpful in such cases.
- Medium-Chain Acyl-CoA Dehydrogenase (MCAD) deficiency is a very rare enzyme defect which makes it difficult for the body to process fatty acids which are mobilised during a fast. In such cases urine may appear light in colour which is unusual during a fast when great deal of waste (ketones) are being processed.Extreme lethargy and vomiting are early signs. Such problems would only present a danger on a long fast, and not during a short (48 hour) fast because the mobilisation of fats would not be advanced until some days of fasting.
- Long fasts are contraindicated in anyone with severe liver disease or severe anaemia, however repetitive short fasts may be beneficial as part of an overall strategy to assist or normalise such problems.
- There are strong contraindications to even short-term fasting for anyone who is taking prescription drugs. If a health condition is such as to warrant regular intake of such medication then the condition should be treated in such a way as to avoid long fasts or unpredictable reactions could occur. This is particularly true of anyone taking steroid medication, or who has taken steroid medication in the past for long periods. A similar caution is required regarding anyone taking forms of hormone replacement, such as in cases of underactive thyroid.
In all such cases (where steroid - hormone medication is current of has been prolonged) supervision of the fast is essential, in a controlled environment - clinic, hospital etc. whether or not weaning from the medication has been possible prior to the fast.
Physician Joel Fuhrman MD explains his approach to patients on medication if he wishes to have them fast,