Fasting for Health and as an Anti-Aging Strategy

Fasting is arguably the most natural and effective health enhancing measure available – or at least it was. Lengthy fasts, up to 100 days, used to be carried out regularly with spectacular results and usually following a predictable pattern.

Because of the accumulation in the fatty tissues of almost everyone on the planet of toxic debris from petrocarbons to dioxin and DDT fasting may not be such a safe option any longer, or at least lengthy fasts which produce an uncontrolled delivery of the toxic debris into the bloodstream may no longer be safe unless under strict supervision.

There are arguably only three broad strategies which can offer a beneficial change to the inevitable decline in health caused by biochemical, mechanical (posture etc) and emotional stressors impacting anyone’s defense systems:

  1. Removal of causes (improved nutrition, exercise patterns, relaxation) so reducing the demands being made on the adaptive, repair and defense capabilities of the body.
  2. Improvement of the adaptive, repair and defense capabilities of the body by methods which enhance immune and repair functions.
  3. Treatment of the symptoms – either in a way which causes no new problems (the ideal) or in ways which mask symptoms and actually create new problems, depending upon which model of health care you follow.

Natural Healing Objectives

Unlike the use of medication and much surgical intervention which impose solutions, or which makes forced alterations to particular situations, natural healing methods have a respect for the self-healing (homeostatic) potentials of the body.

This is sometimes referred to as ‘vis medicatrix naturae’ or the ‘healing power of nature’. In German texts it is often referred to as ‘awakening the physician within’, and in more scientific terminology as ‘enhancing homeostasis’.

Such methods appear to work by allowing space, giving a healing opportunity and doing the opposite of forcing a solution, which may offer only short term benefits.

Fasting sits at the centre of such approaches, along with relaxation and meditation methods, the use of relaxing hydrotherapy methods (such as the ‘neutral bath’), the use of non-specific bodywork (‘wellness massage’ and aromatherapy relaxation methods for example) and employment of techniques which have a balancing, harmonising, normalising influence – including some herbal and acupuncture methods. None of these methods, in themselves, is ‘curative’, but all allow a healing potential to operate more efficiently because they offer the body-mind complex physiological rest,essential time, space and reduced demands which encourages normalisation and recovery, irrespective of whatever is wrong.

This is not to say that such methods can produce absolute remedies in all cases, since in many instances pathology will have created so much change, so much damage, that the best that can be hoped for is that matters do not get worse, or that there is a marginal improvement. This is nevertheless an infinitely better outcome than a steady decline into ever more ill health.

Trevor Salloum ND describes the benefits of fasting,

“Decreased weight, clearer skin, increased elimination, tissue repair, decreased pain and inflammation, increased concentration, relaxation, plus spare time and savings in the cost of food.Perhaps the greatest benefit is the satisfaction that you are taking a major role in improving your health.”(1)

The Aging Arocess – and Fasting’s Anti-aging Potential

There are a number of competing theories as to just what constitutes the mechanics of the aging process, but there is an increasing agreement that it is probably a combination of interacting elements – all happening at the same time. This was neatly summarised in Newsweek (March 5 1990) by journalists Sharon Begley and Mary Hager,

“One theory holds that the changes that accompany aging are the inevitable result of life itself. DNA, the molecule of heredity, occasionally makes mistakes as it goes about its business of synthesising proteins; metabolism produces toxic avengers (free radials) that turn lipids [fats] in our cells rancid and proteins ‘rusty’. This damage accumulates until the organism falls apart like an old jalopy….The other theory argues that aging is genetic, programmed into the organism like puberty. there is evidence for both sides.”

So we either gradually start to malfunction and fall apart because of wear and tear and the effects of accumulated toxic materials, and/or the whole process is as inevitable as growth, puberty and the menopause – it is preprogrammed in our cells.

Research into how to slow down this inevitable process has been focusing ever greater attention on to what has been termed ‘calorie restriction’ as a means of successfully reversing (or at least slowing) the decline into decrepitude and death.

The principle researchers in this field are Americans Richard Weindruch PhD and Roy Walford MD. (2)
I have summarised their work and added other evidence to support the value of ‘calorie restriction’ (which includes the use of fasting, monodiets and exclusion/elimination diets) in my own books on the subject, Natural Life Extension and my detoxification text Body Tonic (formerly published by GAIA as Clear Body Clear Mind)(4)

Short Fasts? Long Fasts?

Fasting for longer than two days can hardly ever cause harm, although some short-term symptoms might be noted, as will be discussed later.

Some experts say that up to five days of unsupervised fasting is acceptable – however I disagree and insist that no-one fasts for longer than four days without the advice and potential for supervision from a health care professional who is qualified to give advice, in case symptoms of an unpredictable nature start during a fast.

And What Are The Risks?

In the medical literature up to 1985, involving thousands of cases of fasting, usually involving severely ill patients often with life-threatening conditions, there are only 7 cases of death reported and in five of these drugs were administered during their fast, something which is quite definitely contraindicated. (4), (5), (6), (7), (8)

As Joel Fuhrman MD explains,

“If we look at the details of these cases we can clearly see that the individuals were fasted improperly, using multiple drugs during the fast, in patients who had heart failure and kidney disease prior to the fast…..[some of] these patients drank unrestricted amounts of coffee, tea, and fruit juice during the fast and were given digoxin, diuretics and anticoagulants. These were not total fasts, and might more appropriately be called coffee and fruit juice feasts.”

A statement taken from the ultra-cautious and medically conservative journal The Lancet (9) helps to put into context the relative danger,

“Fasting short of emaciation is not hazardous, if death results, reasons other than those of the fast should be considered before concluding that all supervised fasts should be discouraged.”

And remember that NONE of these tragedies were related to short term fasting, which is the most highly recommended tactic for home use.
ALL long-term fasting needs to be performed under supervision by a qualified and experienced health care professional.

Contraindications to Extended (beyond 48 hours) Fasting

  1. 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.

  2. 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.

  3. 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.

  4. 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.)

  5. 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.

  6. 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.

  7. 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.

  8. 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,

    “Normally, I taper medication as the patient adopts a healthy diet and postpone the fast until it is safe to discontinue most medication…….If patients cannot reduce their dependency on such agents [toxic drugs which combined with fasting can cause toxic insult to the kidneys] through dietary and nutritional management prior to the fast, they are not suitable candidates for a fast.”(10)

    Among the forms of prescription medication which indicate that fasting should be avoided would be the current use of antidepressants, non-steroidal-anti-inflammatory drugs, aspirin, oral hypoglycaemic drugs, anti-coagulant drugs, chemotherapeutic drugs, anti-hypertensive medication.
    Once these have been safely stopped, with a physicians approval, fasting can commence, however if the fast is to last for more than 48 hours supervision is suggested.

  9. Anyone habitually using ‘social’ drugs (alcohol, tobacco, street drugs etc) should be very carefully detoxified (as well as stopping the habit) before any long-term fasting is considered. All signs of withdrawal should be passed before fasting is used, and careful monitoring of their condition should be continued throughout long-fasts. Short fasts, interspersed with other detoxification method are preferable.

  10. No-one who is afraid of the idea of fasting should be asked to do so. There are gentler ways, including mono-diets which can start the process.

Common Side-effects of Fasting

Awareness of the likely side-effects of fasting is important for both the person undertaking the fast and anyone supervising or looking after them. Such ‘side-effects’ are usually relatively mild and are rarely serious, and include:

  • Headaches (usually lasting less than a day – and common at the start of a fast). Cold compresses, warm foot baths and neck massage should help.

  • Insomnia is not uncommon at the start of a fast. A ‘neutral bath’ is often helpful as are the use of essential oils.

  • Nausea and a coated tongue are usual on a fast. Scraping the tongue and use of a herbal mouth-wash can help reduce these symptoms. Gentle acupressure on the ‘anti-nausea’ point (P6) on the wrist should help minimise this symptom.

  • Dizziness, lightheadedness and palpitations are common early symptoms and highlight the need for rest and for no driving or use of machinery requiring strength or concentration during a fast. Relaxation and slow deep breathing exercises are suggested to assist in the normalisation of these transient symptoms.

  • Increased body odour, skin rashes and dry skin may appear during a fast. Regular warm but not hot showers or aromatherapy baths using appropriate oils are suggested. All such symptoms decrease as regular short fasts are undertaken.

  • Increased discharge from mucous membranes (nasal, vaginal etc) often occurs and this should be allowed to happen unchecked.

  • Aching limbs and muscles may occur and can be minimised by use of aromatherapy oils in a neutral bath, massage and doing light stretching exercises.

  • It is normal to feel colder than usual during a fast so the individual should dress more warmly than usual and add an extra blanket to the bed.

  • As a rule hunger vanishes after the first day of a fast.

  • Bed-rest is not essential or even desirable unless the physical condition demands it. Fresh air and a little gentle exercise are helpful but excessive exercising (aerobic) and sunbathing should be avoided to conserve energy and prevent dehydration.

  • The bowels may stop functioning during fasting and this is not a concern. In long fasts if there is a history of a toxic bowel an enema or colonic irrigation may be suggested, although this is seldom necessary.

Possible (rare) Side Effects During Long Fasts

  • If serious symptoms occur on a long fast, such as a sudden drop in blood pressure, or a feeling of extreme cold which persists, or a prolonged, rapid and weak pulse, or extreme weakness, or difficulty in breathing then the fast should be stopped. These symptoms are unlikely to occur on short fasts, but are possible on long-fasts which highlights the need for supervision and the regular checking of vital signs.

  • If vomiting and/or diarrhoea occur and are persistent then expert advice should be sought. It is essential to maintain liquid intake at an optimum level.

  • If acute anxiety and emotional distress are experienced then the fast should be carefully broken (vegetable broth, yogurt, steamed fruit etc).

  • If there are signs of hepatic or renal problems the fast should be terminated.

  • Uric acid levels in the bloodstream rise during a fast and if there is a history of gout caution is required. High levels of fluid intake can ensure that gout is an unlikely outcome of fasting even if uric acid levels become relatively high.

Lab Tests During Long-term Fasting (more than 4 days)

  • Salloum, Burton and Fuhrman as well as many other experts suggest that during a supervised long fast there should be daily assessment of vital signs (heart, blood pressure etc) and weekly evaluation of electrolyte levels and reserves (which should be repeated if vomiting and/or diarrhoea or sudden weakness are noted)

  • Before a long fast is started liver and kidney tests should be performed. A long fast should be ruled out if the liver or kidneys are in a distressed state.

  • No specific patterns of laboratory results are predictable during a fast, with individual characteristics being evident depending upon overall health status and any concurrent medical problems.

  • Liver enzyme levels may rise, with or without liver disease being present.

  • Cholesterol and triglyceride levels usually rise as fat stores are mobilised and uric acid levels rise (they should all fall after the fast).

  • Blood glucose levels decline in most fasting individuals (and normalise subsequent to the fast).

  • Erythrocyte Sedimentation Rate (ESR) usually decreases during a fast while most aspects of complete blood count remain stable if hydration is adequate.

  • Increased specific gravity of urine usually indicates inadequate hydration. A variety of unusual products are commonly found in urine during a long fast.

  • Insulin and thyroid hormone levels usually drop during a fast, while growth hormone increases (except in obese patients). Other increases usually include serum melatonin (assisting sleep and stress reduction), glucagon, cortisol, plasma norepinephrine.

  • Blood pressure is likely to drop as is weight and pulse rate.

  • A marked improvement occurs in immune function, especially during the first 36 hours of a fast. There may be raised levels of T-lymphocytes and lymphokines, decreased complement factors, decreased antigen-antibody complexes, increased immunoglobulin levels, enhanced natural killer cell activity, heightened monocyte killing and bactericidal activity and marked increase in resistance to infection in the post-fast period.

Despite this apparently lengthy list of possible dangers and side-effects

fasting is safe, and short term fasting is almost totally safe.


  1. Salloum, T. Fasting – Patient Guidelines Textbook of Natural Medicine (eds Pizzorno J Murray M) Bastyr University, Seattle WA. 1987.

  2. Weindruch, R. & Walford R The Retardation of Aging by dietary restriction. Charles Thomas Springfield Illinois. 1988.

  3. Chaitow, L. Natural Life Extension Thorsons 1992 & Clear Body Clear Mind GAIA London. 1991.

  4. Burton, A. Fasting too long Health Science 2:144-146. 1979.

  5. Cubberley, P. et al Lactic acidosis and death after treatment of obesity by fasting New England Journal of Medicine 272:628-630. 1965.

  6. Norbury, F. Contraindications to long-term fasting JAMA 188-88 1964.

  7. Kahan, A. Death after therapeutic starvation The Lancet i:1378-1379 1968.

  8. Salloum, T. Burton A Therapeutic fasting Textbook of Natural Medicine (eds Pizzorno, J.; Murray, M.) Bastyr University, Seattle WA. 1987.

  9. Stewart, W. Fragmentation of cardiac myofibrils after therapeutic starvation Lancet i:1154. 1969.

  10. Fuhrman, J. MD Fasting and Eating for Health St. Martin’s Press NY. 1995.

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Written by Leon Chaitow ND DO MRO

Explore Wellness in 2021