Great healing power is attributed to the temporary cessation of food intake. Some believe that life can be prolonged in this way. This is not proven.
Ash Wednesday is approaching. This is the period when the Christian West traditionally reduces food intake. But variants of fasting belong to almost every culture, every religion.
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At present, certain variants are becoming increasingly popular. With God, religion and spiritual self mortification this has then usually rather little to do. The renunciation should rather help to lose weight, work against all possible illnesses or not let them develop at all. It is supposed to make people healthier and fitter overall, possibly even prolonging their lives. But what is really known about the healing power of fasting, and what is not? An overview.
What was the purpose of fasting in past times?
Fasting rules have been handed down from ancient Egypt, for example, the prescribed renunciation of fish during the spawning season in the Nile. The Christian Lent, in which religiously justified in the 40 days before Easter no meat is to be eaten, had according to opinion of Anthropologen above all the sense to receive the cattle existence. At the end of winter, other supplies were often exhausted, but livestock remained as a store of calories. This was to be protected with foresight.
About the sows were pregnant during this period. The guaranteed protein supply for the year – if the farmer fed them and let them live. However, these pragmatic reasons are certainly not the only ones. Almost every religion and almost every region of the world knows certain fasting practices.
And it is at least conceivable that these were a kind of early "public health" measure, because people had accumulated experiential knowledge about the health-promoting effects of fasting over centuries and millennia.
Is there "fasting in nature?
With very many animal species more or less long hunger phases occur again and again or also regularly. Predators, for example, do not necessarily always manage to make prey when they are hungry.
Even herbivores can run short of food in times of drought.
Animals that hibernate have very long periods of fasting genetically programmed into their behavioral repertoire and metabolism.
Even among the ancestors of today’s people, food abundance and food shortage often alternated. Those who were able to endure the latter best, and who finally managed – even partly with their last reserves – to get food again, survived best, reproduced and passed on their genes.
It is probably thanks to this evolutionary heritage that we humans are now able to go without food voluntarily and without harming ourselves over long periods of time.
Today’s fasting disciples regularly report how positive their mood is, how mentally clear and focused they are – but also how physically fit they are – on days without food intake. This also makes evolutionary sense. For it was precisely in the hunger phases that it was important to be optimally able to obtain food again at this time.
So today, when a Silicon Valley CEO like Twitter boss Jack Dorsey talks about his highs and clear thoughts on his zero-calorie days, he’s basically a purely biochemical image of a hungry, go-anywhere hunter in the savannah world of our ancestors.
How to explain the current renaissance of various fasting practices?
The reasons why more and more people seem to be interested in fasting are probably manifold. Renunciation in the face of ubiquitous abundance – at least in countries where no one has to go hungry involuntarily – is likely to play a role, as is the search for spiritual fulfillment even without concrete religious doctrine.
Many see the chamfering, because calories are renounced, simply as comparatively straight possibility of losing weight. The increasing reports that temporarily abstaining from food could be healthy and even prolong life are probably the most significant factor.
What happens in the body during fasting?
After long hours without food intake, the body adjusts its energy metabolism. It no longer uses glucose from dietary carbohydrates, but instead converts fats in the liver into so-called ketones. They can supply almost all body cells with energy. In addition, molecules are released that protect cells, because the lack of food puts those cells under stress.
An important factor is that – precisely because no sugar enters the blood via the intestines – no insulin is released. In this state, the body can better break down and digest damaged cells. In addition hereditary property is repaired. These stress defense reactions, also called hormesis, are considered by many researchers to be the actual reason why fasting seems to have positive health effects.
What types of fasting are there?
To the classical and in view of Vegan movement and climatic protection to new meaning gotten omission of meat in the meantime numerous further variants join themselves. This includes cures lasting several days or weeks with almost no calorie intake. These are also offered by certain specialized facilities and are usually accompanied by other treatments such as the administration of laxatives and liver wraps, as well as adapted exercise programs.
For them, however, you usually have to leave your everyday life completely. Among the religiously based variants is the abstention of Muslims from food and drink during the day at the time of Ramadan. This is basically a form of the currently secularly very popular so-called interval fasting. Meant with it the regular alternation of longer than otherwise between meals usual periods, in which food admission is avoided, with such, in which it is permitted.
Why intermittent fasting in particular is so popular at the moment?
With the Intervallfasten there are the most diverse variants. In the one known as "5:2," a week has five days of normal food intake and two of very limited calorie intake. Another version means not eating anything all day once or several times a week.
This amounts to about 36 hours of fasting each day, as the evening without dinner is followed by a night of fasting. In the 16:8 fast, the daily window of opportunity for eating is limited to about six to eight hours. All these types of fasting are popular, among other things, because they are relatively suitable for everyday use, unlike the above-mentioned cures of many days.
The body can also adjust its metabolism better if the last fasting period was not long ago. Because then the necessary enzymes and activated genes are still available to him.
The fact that Interval Fasting is propagated by celebrities also plays a role. In addition it comes that in the last years the positive messages from the science pile up. A recent review study in the New England Journal of Medicine, the world’s most respected medical research journal, concludes that interval fasting has many health benefits and may even prolong life.
What scientific evidence there is of health-promoting effects?
"Heal a small pain rather by fasting than by medicine" is already written in the Hippocratic writings. In the meantime, however, some physicians and epidemiologists attribute a far greater potential to fasting. It should be able to prevent practically all large people diseases and also help to get them in the grasp, if they are already broken out.
In fact, there is very clear evidence from numerous studies with laboratory animals that when these animals were forced to engage in interval fasting, they became less ill than conspecifics who ate normally. Even tumors did not grow or grew less.
But laboratory animals are not human beings. The scientific data that exist from studies with humans at least show that, for example, overweight people lose weight, that it can have a positive effect mentally – and that numerous blood values change in a way that is at least considered beneficial to health. These include insulin, blood lipids, cholesterol and some inflammation-regulating substances. In addition, studies have found improved ability to remember concepts in older people.
What is the evidence for "rejuvenating" and life-prolonging effects?
For a long time it is discussed whether a permanent less of food is healthy and prolongs the life. This is indisputable with worms, even with mice.
In humans, there have been impressive anecdotal reports for centuries. Here to mention would be for example the writings of a gentleman named Luigi Cornaro, which in the 15. and 16. He lived in Padua in the thirteenth century. After a rather full youth, his doctors had predicted his imminent death at the age of 35. Cornaro then prescribed himself a strict diet. He lived to be 100 or even 102, and enjoyed quite good health until almost the end.
It’s a nice story, made even nicer when you know that three glasses of red wine a day were allowed. But neither in Cornaro’s time nor today are there studies with people that would turn such anecdotes into assured knowledge.
Much of what is known about fasting fits plausibly into the reasoning of those who see it as a fountain of youth: Processes are promoted that dispose of cellular waste and promote hereditary repair. Molecules are formed that neutralize free radicals. Increased growth factors are formed, which, among other things, ensure that brain cells grow and close connections. And much more.
But nobody knows whether all this makes a fasting disciple a Cornaro, or whether Cornaro owed his health to good genes and luck until he was over 100. Because corresponding studies would be very costly and lengthy, this will remain so for the time being. Because one would have to accompany each quantity of persons from their youth up to their as late as possible death very intensively and document in detail, what and how much they eat and which other factors perhaps also play a role.
Are there other advantages?
Sociologists and psychologists see positive aspects above all in the conscious confrontation with one’s own body, but also with issues such as abundance and hunger in the modern world. It is indisputable that not eating whole meals and preparing them – unless you have to cook for the children or other relatives anyway – frees up time resources.
What the critics say?
For a very long time, conventionally trained physicians considered abstaining from food to be fundamentally unhealthy. The arguments for this were not particularly complex, but boiled down to one thing: If you don’t eat for more than a few hours, you will develop a "catabolic metabolism". That means: Body substance is broken down, and here not only fat, but also protein from the muscles.
Catabolic metabolism leads to death in the long term and is characteristic of some serious diseases, such as advanced cancer. Also at short notice it can come already to the discharge of toxins and a general weakening. The study results mentioned and realizations over the metabolism and the biochemistry let many physicians correct this view.
Important points of criticism at present are that there are many studies, but they only deal with body weight, blood sugar, blood lipids and the like. "Surrogate parameters" is what the Heidelberg diabetologist Peter Paul Nawroth calls such values. For they say nothing about whether people who fast regularly really do better than those who do not, whether these people are really less ill in the end, less likely to get a heart attack or diabetes complications, or more likely to be spared dementia.
In addition there is so far simply "no data", so Nawroth. Also nourishing physicians are the opinion that still many questions are open. In addition, most studies in which fasting variants were tested on humans lasted only a few months. So there is not even good data of those "surrogate parameters" in the long term. From a purely practical point of view, the studies so far also show that it is not necessarily easy to maintain such a dietary routine over the long term.
In a recent study, however, Intermittent Fasting worked at least about as well as the Mediterranean diet with lots of vegetables, vegetable oils and fish, which is also considered to be beneficial to health.
Who should renounce fasting?
In otherwise healthy individuals, studies have so far failed to demonstrate any adverse effects even in the course of strict interval fasting.
One of the most controversial fasting variants is the "Breuss cure", which is recommended to cancer patients by some advocates of so-called alternative healing methods. It consists of 42 days without solid food and a little vegetable broth every day and is supposed to starve the tumor, as it were. It often does, at least there are reports of shrinking tumors.
But what also shrinks is the other physical substance of the patients and the strength of their immune system. And if these eat again, the tumor is still there and often comes back with deadly force into the emaciated body.
In studies, the blood values of diabetics have improved considerably. But especially they should fast only under medical supervision because of possible complications.
Fasting seems to be generally disadvantageous for children, who are growing and have few reserves.
Culturally traditional fasting practices seem to reflect this finding. In Ramadan, for example, unlike adults, no child actually has to abstain from food and drink throughout the day before reaching puberty. If this happens nevertheless, then by religious overzealousness.
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