Surely, we wouldn’t be populating the planet in such vast numbers if our ancestors, prehistoric humans, had retreated to their caves apathetically and depressed whenever they experienced hunger. Instead, their brain became especially active—a zest for action is probably one of the best ways to ensure a successful hunt for food.
Part of the reason for this emotional contentedness during fasting is due to increased serotonin in the brain. In a study from 1997, Gerald Hüther was able to show that under calorie restriction and fasting conditions, serotonin is released in increasing amounts in the brain. But there is also an increased production of endorphins, i.e., opiates, in the body during fasting.51 In addition, one of the most renowned brain researchers and neurobiologists in the world, Mark Mattson, was able to demonstrate in countless experiments in his laboratory that nerve growth factors contribute significantly to brain health and positive mood.52 The most famous of these nerve growth factors is the BDNF (brain-derived neurotrophic factor). Regular exercise as well as fasting and calorie reduction cause a distinct increase of BDNF levels.
But that’s not all: Test animals in Mattson’s laboratory that fasted intermittently showed a significantly lower risk of developing Parkinson’s disease, multiple sclerosis, or Alzheimer’s at a later stage. Even non-avertible genetic diseases like Huntington’s disease could be delayed in the test animals by repeated fasting.53 In a 2016 study we conducted together with Valter Longo’s research team and the NeuroCure research team at the Charité Hospital, we were able to demonstrate that therapeutic fasting followed by either a healthy Mediterranean diet or a vegetable-heavy, ketogenic diet could improve the condition and quality of life of patients with multiple sclerosis.54 In an ongoing study we are examining how this progresses in the long term. All of these are indications that fasting is a promising new treatment method for nervous diseases.
THE RIGHT WAY TO FAST
Fasting has suddenly become fashionable in the world of medicine, particularly in the United States and Europe. Experts who had been criticizing fasting as dangerous only a few years ago have now switched sides and are in support of fasting. What happened? The shift is due to the impressive experimental data available. I must emphasize here that, even though different ways of fasting have demonstrated excellent effects in animals in lab situations, the results are not so easily transferable to humans. Among other factors, the lifespan of animals is not identical to that of humans. Twenty-four hours of fasting mean something different to a mouse than to a human. So even though it has been shown that intermittent fasting is good for the body, it’s much more difficult to say which way to fast is the best.
How should we feel about diets that imitate fasting? Valter Longo has published a tremendous amount of research on the fasting-mimicking diet. We can say with almost absolute certainty that large parts of the positive effect of traditional fasting are due to the fact that sugar (by which I mean not only standard sucrose but also the sugar into which carbohydrates are broken down into) and animal proteins are missing from the food consumed. A second point is that reducing calorie intake by 50 to 70 percent appears to generate most of the beneficial effects of total fasting without the adverse effects. Together with a California company, Valter Longo consequently developed fasting-mimicking dietary concepts for prevention (ProLon) and for chemotherapy (Chemolieve) that include a complete daily package of ready-made food containing about 600 to 800 kcal for four to five days of “fasting.” Longo, who donates his profits from these companies to a foundation dedicated to the support of research on fasting, believes that it’s only by using such ready-made meals that regular fasting can be accomplished successfully over the entire course of one’s life.
Both options are probably important for the integration of the powerful fasting therapy into medicine. For people looking for self-help treatments, traditional fasting might be the preferred way. However, for people who suffer from chronic diseases such as inflammatory, metabolic, cardiovascular, or oncological diseases, a fasting-mimicking diet might be preferable. For people who want to fast on a regular basis for prevention, both options are possible—you can develop a fasting cuisine that caters to your individual tastes or choose the fasting-mimicking diet. Most likely, further fasting-mimicking diets, tailored to a variety of disease states, will be developed by Longo and hopefully reimbursed by health insurance companies in the future.
The hope of enjoying the positive effects of fasting without having to forsake food has yet to be fulfilled. Apart from “imitated fasting” (fasting-mimicking diets), the closest we’ve come to a drug that mimics the effect of fasting is the diabetes drug Metformin, which, due to its uncertain effect on intestinal bacteria outside of a diabetes treatment, should be considered with skepticism. Resveratrol, a phytochemical derived from the skin of grapes, is also meant to reproduce the anti-aging effect of fasting. But the necessary dosage is high and could not be achieved without other risks—particularly if taken in the form of wine.
MY RECOMMENDATIONS DERIVED FROM MEDICAL EXPERIENCE
Based on naturopathic tradition and my own experiences, it seems best to combine therapeutic fasting under medical supervision or regular cycles of the fasting-mimicking diet with intermittent fasting in everyday life. For example:
One to two weeks of therapeutic fasting once or twice a year to support the treatment of chronic diseases such as rheumatism, psoriasis, fibromyalgia, diabetes, hypertension, pains, migraines, or irritable bowel syndrome.
In addition, intermittent fasting in everyday life (also suitable for healthy people as a method of prevention): Omit dinner or breakfast so that you don’t ingest any food for a period of at least fourteen hours (that includes not drinking any alcohol). In general, you should only eat when you are truly hungry. Abstain from having snacks here and there. Moreover, have a day of fasting or cleansing once a week and eat only rice and fruit—but no more than 800 kcal; alternatively, have two such days a month.
Ideally, you should undergo therapeutic fasting in its entirety, by submitting yourself with serenity and concentration. Healthy people should fast anywhere between five and seven days. In specialized clinics, this period can be extended to two to four weeks. The more substantial a person’s fat reserves, the easier fasting is for them and the longer they are able to do it. Some people even fast the biblical forty days. Even though some of my out-patients have told me about this euphorically, it seems too risky to me. I would advise against it.
During those days of fasting, you’re not on a calorie-free diet. Instead, you ingest about 250 to 400 kcal a day in the form of liquid meals. The most established is the technique according to Buchinger: In the mornings and evenings, you are allowed to drink a small glass of fruit or vegetable juice; at lunch, strained, unsalted vegetable broth. Over the course of the day you should drink two to three liters of liquids, herbal teas, and still water to support the flushing of the kidneys. (I do not recommend drinking coffee or other caffeinated beverages while fasting, as it might lead to stomach complaints.) According to our studies, this is even more effective if you don’t drink sweet fruit juice but only vegetable juice so as to achieve a more powerful lowering of insulin and IGF-1 levels. But this can be handled according to individual tastes. In fasting, not everything is beneficial and agreeable to everyone. If, for example, you have a sensitive stomach and the juices cause you problems, you might want to substitute juice with small amounts of oatmeal or rice gruel.
How Fasting Affects the Body
Brain
Increases the growth factor BDNF; changes the messenger balance; enhances mood; stimulates production of nerve cells; prevents dementia
Liver
Stimulates production of ketone bodies and breakdown of glycogen as an alternative source of energy; leads to reduction of the growth hormone IGF-1
Pancreas
Decreases production of insulin; allows for recuperation
Joints
&n
bsp; Counteracts rheumatism and arthritis; relieves pain
Cardiovascular system
Lowers blood pressure and cholesterol levels; lowers the heart rate (pulse); improves heart rate variability
Gastrointestinal tract
Increases diversity of intestinal bacteria
Fat tissue
Leads to fat reduction; changes to messengers (e.g., decreased production of leptin; anti-inflammatory)
I no longer recommend the classic Franz Xaver Mayr diet, where you eat stale bread rolls and milk. Since more recent studies attest to the fact that omitting animal proteins contributes significantly to the beneficial effect of calorie reduction, it would be paradoxical to drink milk during fasting. Newer variations of the Mayr diet take this into account and substitute dairy milk with almond milk and oat milk.
I do not advise a pure starvation diet, since this facilitates increased and unnecessary muscle reduction.
A lot of patients will tell me about other fasting cures, such as the alkaline diet. This entails several days of eating a vegetarian diet with a lot of root vegetables and no bread. This may certainly be healthy, but it cannot be considered therapeutic fasting because it lacks the essential aspect of reducing calories to less than 500 kcal a day. And this caveat is a major one, because you want to achieve the reduction of endogenous fat and the other beneficial effects prompted by the slight “stress of fasting” on a cellular level. Not only are other new or even traditional fasting methods nonsensical at times, they can also be dangerous. The traditional Schroth cure, for example, consists of taking turns between drinking and dry days, and on drinking days you are encouraged to consume two glasses of wine. At best, this is good for your mood, but not for your body.
It is important to ensure sufficient exercise during fasting. Thereby, the increasing amount of acid that builds up in the body is expelled better through the lungs. There are many more ways in which exercise and fasting complement one another exceptionally well in stimulating cellular repair mechanisms. But it’s important to find a good balance between rest and exercise. Some people feel so energetic during fasting that they have no trouble going to work. For others, it’s better to visit a monastery, a hotel, or a clinic, and free themselves from all duties and stress (and especially from their smartphone). In general, stress reduction is an essential part of fasting. I thoroughly recommend practicing a relaxation program such as yoga, meditation, tai chi, or qigong during fasting for at least an hour a day.
ARE ENEMAS NECESSARY?
In the European tradition, each fasting period is meant to begin with a “bowel cleanse”: taking a laxative salt such as Glauber or Epsom salts. (As a side note: Since biliary secretions increase significantly during fasting, people with small gallstones should opt for a gentler way to start fasting, with Epsom salts rather than Glauber salts, or a preparation similar to the one used before a colonoscopy. Likewise, people with a predisposition for gout should undergo fasting only with medical supervision.) During the fasting period, it is usually recommended to have an enema every second day. The bowel intensifies its wave-like contractions, its peristalsis, after the intake of food. Everyone has experienced this when the urge to have a bowel movement occurs in the mornings or around noon just after having eaten something. This is called the gastrocolic reflex. During fasting, this intestinal movement is slowed down drastically. With the salts or, alternatively, with an enema, the remains of earlier meals are delivered from the body thoroughly.
There is no data on whether such a procedure improves the success of fasting, medically speaking. Research on this is also influenced by culture. In the United States, for example, people seem to back away from bowel cleanses of any kind because it’s such a taboo subject. One disadvantage of emptying the bowel is the loss of minerals and trace elements. I have also observed temporary (benign) dysrhythmias or cramps in the calves. That is why I generally advise a gentle dosage. People with sensitive bowels or who never suffer from constipation and have regular bowel movements don’t necessarily need this initial, more intense bowel cleanse. But it’s part of the ritual, after all, and it can make the beginning of the fast easier, since it lessens the feeling of hunger. Plus, the feeling of having one’s bowels emptied is a pleasant one. The subsequent enemas are appreciated by most people who fast, but in my opinion they are irrelevant to a successful fasting period.
In some fasting clinics, colon hydrotherapies are carried out, where the bowel is cleansed by mechanical irrigation. These are hardly useful. There is no evidence that fasting is improved by this. At most, they provide good additional income to the clinic. The positive results of fasting aren’t caused by “flushing away” or “expulsion,” but play out invisibly, on the cellular and molecular level.
Midday liver compresses are a powerful supplement to traditional therapeutic fasting: A damp, warm compress in the liver area (applied while resting or lying down for over thirty minutes) improves blood supply to the liver and the gallbladder and intensifies metabolism. Sweating in a sauna or a steam room also supports this process. Blood flow to the skin can be facilitated by massaging the skin with a dry natural hair brush every morning. Similarly, you can brush your tongue (with a toothbrush or a tongue scraper). During my rounds, I see the coating on our fasting patients’ tongues change daily. The tongue is a kind of “window” into the intestine—it indicates active metabolic processes. Therefore, cleaning the tongue every morning is useful so you can reduce the bacterial load of the tongue and enhance the cleansing function of fasting. What is not necessary, however, is taking pills or vitamins of any kind. Fasting is holistic and complete all by itself; it does not require any supplementary medication. This also applies to alkaline powders. Alkaline powders can indeed be an appropriate supplementary treatment for chronic kidney diseases, diabetes mellitus, or osteoporosis, since they reduce the acid load that is part of a diet heavy on meat and bread. During fasting, however, the occurrence of acids is a desired part of the transformation process. In a controlled study that I conducted while working in Bad Elster, I compared the overall well-being of one hundred patients who were fasting normally with an equally numbered control group whose participants, in addition to fasting, were given an alkaline powder three times a day. The control group’s urine was indeed not as acidic, but otherwise the alkaline powder had no effect on their symptoms and their well-being.55 Only when a patient suffers from severe back pain or headaches could alkaline powder or pills be useful, though the headaches that often occur during the first three days of fasting are usually due to caffeine withdrawal. If you drink coffee regularly, you probably won’t be able to avoid this annoying initial discomfort.
In any case, you should begin fasting with at least one so-called “day of relief” (with a light meal of unsalted rice) and factor in two days of rebuilding, in which you eat little, light meals, after ending the fasting period. Otherwise you’ll render part of the beneficial effect void—just like I did as a student.
FASTING IN YOUR SLEEP
My advice is to make use of the night. If you sleep from 11 p.m. to 7 a.m., for example, you’ve already not eaten for eight hours; now you only need another six hours to get to the green zone of fourteen hours. And because it seems like a good idea to not eat too late in the evening, at 7 p.m. at the latest, that’s another four hours between your last meal and bedtime. Only have an espresso or some tea for breakfast, maybe a small piece of fruit. Take your first proper meal at lunch. By that time, you won’t need to restrain yourself: You can eat until you are full. Your weight may stay the same. However, overweight people tend to lose weight this way. In the United States, this method is also known as “time-restricted eating.”
Having said this, researchers disagree on whether it’s twelve, fourteen, sixteen, or eighteen hours of not eating that are ideal. Mark Mattson emphasizes that the longer we fast, the more glycogen stores are emptied, and the more ketone bodies are produced: He advises a sixteen-
hour fast at minimum, but preferably eighteen hours. Valter Longo advocates the more careful method of 12/12, i.e., twelve hours straight without eating and calorie-intake. He argues that it’s harder for people to keep a sixteen-hour break and that they could experience this as stressful, which would then void the positive effect of fasting: “No unhappy fasting!”
The decision is ultimately up to you. Some people may find it easy to cut out breakfast. For others it’s no problem to eat as early as 6 p.m. What’s important is to test different options so you know which one is right for you.
Fasting requires practice—just like exercise. If you don’t feel well after the first two days without breakfast, you should be tenacious and keep going for another two weeks before you draw any conclusions. Only then has the body’s metabolism had enough time to adjust. Our internal clock can shift, as it does when you travel to another time zone. The same holds true for daily intermittent fasting. You should be patient but keep listening to your body. But if you still don’t feel comfortable after a certain amount of time, you should try something else instead.
TWO PROPER MEALS, NO MORE
Scientific opinions vary as to how many times a day one should eat. For a long time, it was believed we should have many small, light meals. You can forget that: It’s outdated. According to the most recent findings, it’s best to only eat two times a day, but have proper meals then. To increase the practicability, Valter Longo allows for another “half” meal, meaning a small portion of a light meal. This, by the way, also corresponds to the recommendations of Ayurveda: In the evenings, you should only have a light, warm soup at most.
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