Discover the MOST INFLUENTIAL Book on Fasting, Natural Healing, and Regeneration!

Prof. Arnold Ehret’s Rational Fasting for Physical, Mental, and Spiritual Rejuvenation: Introduced and Edited by Prof. Spira is one of the most influential works on the healing power of fasting. You will learn:

  • The Common Fundamental Cause in the Nature of Diseases,
  • Complete Instructions for Fasting,
  • Building a Perfect Body through Fasting,
  • Important Rules for the Faster,
  • Why to Fast,
  • When and How to Fast,
  • How Teresa Mitchell Transformed Her Life through Fasting,
  • And much more!
Improve your life!

In this masterpiece, Ehret explains how to successfully, safely, and rationally conduct a fast in order to eliminate harmful waste from the body and promote internal healing. Also included are famous essays on Ehret’s teachings by Fred Hirsch and long-time devotee Teresa Mitchell.

Title Page
 Introduction by Prof. Spira  1
 Preface by Fred S. Hirsch  7
 Part I  9
 The Common Fundamental Cause in the Nature of Diseases  9
 Remedies for the Removal of Fundamental Causes and Prevention of Their Re-occurrence  23
 The Fundamental Cause of Growing Old and Ugly  27
 The Preservation of the Hair  31
 Increasing Longevity  37
 Part II  39
 Complete Instructions for Fasting  39
 Rational Fasting for Physical, Mental, and Spiritual Rejuvenation  41
 Building a Perfect Body through Fasting  45
 Important Rules for the Faster  49
 Rules during the Fast  51
 Short Fasts and the Non-Breakfast Plan  55
 Fasting for Spiritual Rebirth through the Superior Fast  59
 Conclusion  61
 Section II: HEALTH AND HAPPINESS THROUGH FASTING: When, Why, Where, and How to Fast by Fred S. Hirsch  65
 How Long Should One Fast  69
 Why to Fast  71
 When and How to Fast  73
 When to Fast (Part 2)  79
 Why to Fast (Part 2)  81
 Where to Fast  83
 How Long to Fast  85
 Part I: Your Road to Regeneration: Building Bodily Strength and Efficiency by Prof. Arnold Ehret  87
 Part II: My Road to Health by Teresa Mitchell  93
 Build Your Own Road to Health by Teresa Mitchell  107
Fasting is the omnipotent healing modality for animal life. It is a natural and (should be) an instinctual part of life. Yet, nothing is mired in more controversy, misinformation, and miseducation than the subject of fasting. Today, there is little consensus among natural health seekers and practitioners as to what truly constitutes fasting. For some, a diet of mucus-free fruits and vegetables (the mucusless diet) may be considered a level of fasting. For others, a liquid diet of fruit and vegetable juices is a fast. Some assert that consuming only water is true fasting. Yet, others say that dry fasting (no liquids or solid food) is the only real way to fast.

We need not look any further than the works of Prof. Arnold Ehret to find a rational and practical approach to understand what fasting is and how to do it. Ehret does not have a strict or dogmatic definition of what fasting is and is not. In this book, as well its companion text Mucusless Diet Healing System, Ehret discusses a spectrum of fasting experiences, including water, juice, and all-fruit dieting. As a general definition, Ehret asserts that fasting is “simply eating less.”

The word “fast” means to abstain from or restrict the intake of drink and/or food for a period of time. It may also refer to various forms of dietary restriction, which include abstaining from solid foods (juice or liquid fasting), mucus-forming foods (mucusless diet), animal products, and so forth. Fasting is a dynamic concept and may also refer more broadly to abstaining from modern conveniences or unnatural additions, for example, a fast from electricity or the use of electronics for a period of time. In addition to health and healing purposes, various forms of fasting have been a part of many spiritual and religious traditions. Christianity, Judaism, Jainism, Buddhism, Hinduism, Taoism, Islam, Ancient Egyptian Mystery Schools, and more all have strong fasting traditions and many propagate various forms or degrees of fruit dieting.

From Ehret’s perspective, fasting for humans in our current pathological conditions is a relative proposition. Ultimately, it is important to understand the various levels of fasting available to you. What fasting is for one person’s body may not be the same for someone else. As Ehret implied, for some, just eating a mucusless or a fruit-only diet could be a level of fasting. And what is and is not fasting to a person’s body may shift over time as a person’s physiology changes. To determine which fasting regimen is right for you, it is essential to understand the content within this book, which remains the quintessential book on the subject. Through dedicated study and practice you will learn to fast safely and effectively in order to overcome and prevent a myriad of physical and mental illnesses.

Fasting as an Art Form

Fasting may be viewed as a grand art form. There is much more to fasting than merely going without food or drink. Learning to begin a fast properly is very important. Transitioning from a poor to an improved diet before initiating a fast can allow the process to be much more effective. Understanding the role of colon irrigation (enemas) in relationship to fasting is vital. As you begin, it is important to consider the following questions: What is the amount of uneliminated waste in your bowels? Do you have a uric-acid/lean body type or a fatty/mucus body type? (See the Mucusless Diet Healing System for more on body types.) What is the nature of the uneliminated fecal matter still encased in your bowels? Is it made up of the residue of pus-forming foods such as meat and dairy products? Or, are your internal impurities the residue of plant-based, mucus-free foods such as fat- and starch-free fruits and vegetables? Answers to these questions will help you intuitively make rational decisions before, during, and after the fasting process.

There is no greater task within the fasting arts than the ability to eloquently break one’s fast. Fasting too long for your physiological condition only to uncontrollably break it with mucus-forming foods is futile and defeats the purpose of your fast. This is one reason Ehret emphasized “gradual change” toward cleansing mucus-free foods, combined with a series of short, intermittent fasts, for newcomers to fasting and the mucusless diet. As you gain experience with short-term fasting, you will learn how to maintain total control whenever you begin or break a fast of any length.
Do not feel as if you need to do long dry, water, or juice fasts if you are not physically or mentally ready. Strive to do rational fasts based on the needs of your own body. You need not prove anything to anyone, and fasting is not a competition to see who can be food-free for the longest period of time. A lot of people play basketball, but few people think that they should be able to play like Michael Jordan without serious practice and long-term dedication. Many people play music, but few expect to have the virtuosity of a jazz or concert pianist in a matter of weeks. It takes years of dedicated practice to attain the highest levels of any art form. Yet in dietetics, health seekers often feel as if they should be able to skip over the transitional process and sustain long fasts without dedicated practice. Long-term fasting may be a worthy goal, but it should be achieved through fervent practice over a long time. As Ehret pointed out, most people are far too obstructed with mucus, pus, and toxemias for long-term fasts to be very beneficial.

Concepts and approaches similar to that of a 21-day cleanse are problematic and should be avoided. Many people pursue such “cleanses,” looking for a quick fix for losing weight or overcoming a particular ailment. Yet, as Ehret says, ill health issues will continue to emerge as long as a person continues to eat poorly after a fast. In this book, Ehret offers the most rational approach to fasting that can easily be adopted as a regular part of life. When fasting and mucusless diet are applied properly, you can permanently transform what foods you desire. Instead of relying on willpower to avoid wrong foods, you will begin to crave more of the right foods.

History of Rational Fasting

The earliest English version of this book was entitled Rational Fasting and Regeneration Diet, translated from German in 1913. At that time, it was a small book or pamphlet that made up the first part of this edition. In 1922, Rational Fasting: Regeneration Diet and Natural Cure for All Diseases was published. By 1926, Rational Fasting for Physical, Mental, and Spiritual Rejuvenation was a little over 60 pages and divided into two parts, which are represented under Section I in this edition.

Fred Hirsch, Arnold Ehret’s most loyal student and proprietor of Ehret Publishing Company until the 1970s, released subsequent versions—most notably, Rational Fasting for Physical, Mental, and Spiritual Rejuvenation, which included one of his own essays, entitled “Health and Happiness through Fasting.” Subsequent editions have bundled various articles with Rational Fasting, especially “Your Road to Regeneration” by Prof. Arnold Ehret, as well as “My Road to Health” and “Build your own Road to Health” by Teresa Mitchell, both of which are included in this edition.

The Best Way to Use this Book

Rational Fasting goes hand-in-hand with the Mucusless Diet Healing System. You are strongly encouraged to read both texts, subsequently. Understanding and practicing the mechanics of the “Transition Diet” found in the Mucusless Diet Healing System is of the utmost importance to having the greatest success with Ehret’s approach to fasting. I highly recommend examining both books before experimenting with fasting. With that said, this book can and should be read and reread multiple times. The simple yet potent message found in Rational Fasting has the power to elevate your consciousness. And for serious practitioners of Ehret’s methods, this book will seem to transform every time you read it. Of course, it is you—not the book—that is transforming. As you transform your body and mind through fasting and mucusless diet, you will continually breathe new life into this text. Subtle elements that you may overlook the first time you read the book will come to life as you experience improved levels of health and vitality.

The principles found in Rational Fasting are needed today more than ever. In a world where natural healing methods have been largely forsaken by the masses, Ehret sheds light on the powerful art of fasting and its supreme role in regenerating the human body, mind, and spirit.

-Prof. Spira
Summer 2014

Are you one of the thousands of present-age persons discouraged and disheartened because of ill health? Is your faith in so-called cures shattered after having tried them without results? Are you only able to use a small percentage of the vitality that good Mother Nature endows her beloved ones with? Probably you have been told that only an operation will save you. Somehow, when we suffer organic trouble, we fail to think clearly and permit ourselves to be easily persuaded into operations. If you are one of these unfortunates, DON’T GIVE UP HOPE. For “he or she that hath health hath hope, and he or she that hath hope, hath everything.”

“Since humans degenerated through civilization, they no longer know what to do when they become sick.” The genuine principles of healing are simple and few. Our very lack of appetite, which occurs when we are sick, is Nature’s method of teaching her children. One might properly call this a “forced fast.” These are but a few of the truisms taught by Arnold Ehret in his many writings. Our greatest possession is health.
A general agreement seems to be gaining acceptance among an increasing number of practitioners both of the drugless, as well as the medical, fraternity that the fundamental cause of disease is the presence of foreign material in the human body, but it has not as yet led to the discovery of the roots of this invading mystery.

Prof. Ehret has conclusively proven that this disease-causing material is the undigested, uneliminated, and decayed, rotting food elements resulting from too much eating of wrong foods. It is therefore entirely reasonable and should be clearly seen that the main factor in the health enigma should consist of dietetics. If overeating is the main cause of the patient’s disease, it requires intelligently conducted fasts to correct the condition. It is a known fact that all of the animal kingdom living in a natural environment instinctively heal themselves through fasting. It can be easily proven that a person living on a mixed diet of animal flesh and starchy vegetables has a system more or less clogged with mucus. This condition has been going on since early childhood—in fact, even before.

These foods are not suitable for humankind, and they form a sticky, gluey consistency that eventually clogs the circulation. Is it not self-evident and certainly reasonable that this disease-producing eating must be stopped! Fasting, plus a decrease in the quantity of food eaten daily, is the only check on overeating. Exercise due precaution not to proceed too rapidly, for an unwise application of the eliminative process could cause a serious condition to develop.

This drugless healing is not limited in its scope; and through its proper application and use, it restores normal functioning, overcoming practically all ailments to which the human family is subject.


—Fred S. Hirsch


By Prof. Arnold Ehret

Part I: The Common Fundamental Cause in the Nature of Diseases

All the phases of the process of development of medical science, including those of the earliest periods of civilization, have in their way of understanding the causal nature of diseases, that one thing in common: i.e., that the diseases, owing to external causes, enter into the human body and thus, by force of a necessary or at least unavoidable law, disturb the body in its existence, cause it pain and at last destroy it. Even modern medical science, no matter how scientifically enlightened it pretends to be, has not quite turned away from this basic note of demonic interpretation. In fact, the most modern achievement, bacteriology, rejoices over every newly discovered bacillus as a further addition to the army of beings whose accepted task it is to endanger the life of humans.

Looking at it from a philosophical standpoint, this interpretation differs from the medieval superstition and the period of fetishism only in the supplemental name. Formerly it was an “evil spirit,” which imagination went so far as to believe in “satanic personages”; now this same dangerous monster is a microscopically visible being whose existence has been proven beyond any doubt.

The matter, it is true, has still a great drawback in the so-called “disposition”—a fine word! But what we really are to understand by it, nobody has ever told us. All the tests on animals, with their symptom-reactions, do not prove anything sure, because these occur only by means of injection into the blood circulation, and never by introduction into the digestive channel through the mouth.

There is something true in the conception of “external invasion” of a disease, as well as in heredity; however, not in the sense that the invader is a spirit (demon) hostile to life, or a microscopic being (bacillus), but all diseases without exception, even the hereditary, are caused—disregarding a few other hygienic causes—by biologically wrong, “unnatural” food, and by each ounce of overnourishment, only and exclusively.

First of all, I maintain that in all diseases without exception there exists a tendency by the organism to secrete mucus, and in case of a more advanced stage—pus (decomposed blood). Of course, every healthy organism must also contain a certain mucus—lymph, a fatty substance of the bowels, etc., of a mucus nature. Every expert will admit this in all catarrhalic cases, from a harmless cold in the nose to inflammation of the lungs and consumption, as well as in epilepsy (attacks showing froth at the mouth, mucus). Where this secretion of mucus does not show freely and openly, as in cases of ear, eye, skin or stomach trouble; heart diseases; rheumatism; gout; etc., even in all degrees of insanity, mucus is the main factor of the illness. The natural secretive organs unable to cope with it longer, the mucus enters the blood causing heat, inflammation, pain, and fever at the respective spot where the vessel-system is probably contracted owing to an overcooling fever (cold), heat, inflammation, pain, fever, etc.

We need only to give a patient of any kind nothing but “mucusless” food, for instance, fruit or even nothing but water or lemonade. We then find that the entire digestive energy, freed for the first time, throws itself upon the mucus-matters, accumulated since childhood and frequently hardened, as well as on the “pathologic beds” formed therefrom. And the result? With unconditional certainty, this mucus, which I mark as the common basic and main cause of all diseases, will appear in the urine and in the excrements. If the disease is already somewhat advanced so that in some spot, even in the innermost interior, there have appeared pathologic beds, i.e., decomposed cellular tissues, then pus is also being secreted. As soon as the introduction of mucus by means of “artificial food,” fatty meat, bread, potatoes, farinaceous products, rice, milk, etc. ceases, the blood circulation attacks the mucus and the pus of the body themselves and secretes them through the urine; and in the case of heavily infected bodies, even through all the openings at their command, as well as through the mucus membranes.

If potatoes, grain-meal, rice, or the respective meat-materials are boiled long enough, we receive jelly-like slime (mucus) or paste used by bookbinders and carpenters. This mucus substance soon becomes sour, ferments, and forms a bed for fungi, molds, and bacilli. In the process of digestion, which is nothing else but a boiling—a combustion—this slime or paste is being secreted in the same manner, for the blood can use only the ex-digested sugar transformed from starch. The secreted matter, the superfluous product, i.e., this paste or slime, is being completely excreted in the beginning. It is, therefore, easy to understand that in the course of life the intestines and the stomach are gradually being pasted and slimed up to such an extent that this paste of floral and this slime of faunal origin turn into fermentation, clog up the blood vessels and finally decompose the stagnated blood. If figs, dates, or grapes are boiled down thick enough we also receive a pap which, however, does not turn to fermentation and never secretes slime, but which is called syrup. Fruit sugar, the most important thing for the blood, is also sticky, it is true, but is being completely used up by the body as the highest form of fuel, and leaves for excretion only traces of cellulose, which, not being sticky, is promptly excreted and does not ferment. Boiled-down sugar, owing to its resistance against fermentation, is even used for the preservation of food. . .

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Your personal rediscovery of your radiant, intended self is amazing! Living examples, that's what people you are like, timeless individuals who live natural truth and telebeam it to others. . .
Cy, Living foods expert, mother, and registered nurse
. . . I feel like this lifestyle is limitless! It has given me results that I could have never dreamed of a year ago. You . . . have really inspired me and given me the knowledge necessary to get to where I am today. I know I have just scratched the surface to this new lifestyle as I am doing research every day and learning many new things every day.
Andy J. Gorman, Certified Wood Technician and owner of Free Flow Creations
You've changed my life my brother. I'm currently going through a fast because I have had a very mucused diet in the past which has brought out my eczema again. Your videos and writings have woken me up from the matrix I was living in with my diet. Even when I went vegan I was still having skin issues, but after seeing what you have to say about mucus, and why you have to decrease it, it all makes sense.
Nicky Castor Bennett, Health-seeker
Thank you for blessing me! Your recipes are incredible and have given me a new purpose. I'm LOVING it! You truly are amazing. You have done nothing but given all you can to help me and I truly appreciate this. Thank you for feeding me.
Samantha Claire, Pianist and Mucusless Diet Practitioner
The book is excellent! I love the fact that you are so detail oriented. With each page I was learning a lot. Professor Spira, you really outdid yourself and deserve a pat on the back!
Keonna Lo, Health Seeker
Professor Ehret planted the seeds and gave us some tools to start out this new era of re-creating our lives, re-educating ourselves, and re-programing our thinking which was so carelessly messed up by the world we live in. And Professor Spira is the person that picked up from where Arnold Ehret left off and has made everything complete...
Georgia Barretto, Brazilian Jazz Musician
I'm definitely impressed. As simple as you kept much of the language in the text, the writings resonate with me on a much deeper level. The reading forced me to reassess my personal perspective on the subject, and served to challenge all that I previously held to be true. I have much (more) work to do! Thanks again!
Danny Michael , Natural Health Consultant & Dietary Scientist
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