Fasting doesn’t just melt fat deposits. It is also effective against high blood pressure, diabetes and other common diseases. Why fasting for just one day can do a lot – and what happens after forty days.

At the start of the new year, many people decide to eat healthier. Some even consider fasting. However, this is by no means a diet developed by nutritionists that excludes certain nutrients, such as carbohydrates or fat. “No one invented fasting and it is firmly anchored in our genes,” explains Eva Lischka, chairwoman of the medical association for fasting and nutrition and chief physician at the Buchinger Wilhemi Clinic on Lake Constance in an interview with FOCUS online.

Fasting has ensured survival for thousands of years by switching the body to a different metabolic mode during times of hunger.

Fasting is now defined in the guidelines of the ÄGHE as the voluntary renunciation of solid food and stimulants for a limited time. Classic fasting programs are primarily therapeutic fasting in variations according to Otto Buchinger or periodic fasting, with individual days being fasted for up to 16 hours.

250 to 300 kcal per day makes sense.

“Promotion of all elimination pathways, moderate exercise, such as going for a walk in the fresh air, and relaxation exercises round off the program,” adds Eva Lischka. If you are fasting for the first time, it is best to fast in a group during non-working time or according to a good fasting book.

Ultimately, fasting must be distinguished from starvation. Drinking only tea and water and doing without the other components, i.e. not consuming any calories at all, is definitely not recommended.

“Hunger is forced abstinence from food and therefore triggers much stronger stress reactions in the body than voluntary fasting,” the expert explains the difference.

“Additional vitamin supplements are not usually necessary, as there is no digestion work,” says the expert. In patients who are taking medication, a vitamin level check and appropriate supplementation may be indicated, for example vitamin B12 when taking acid blockers.

Anyone who deals with fasting for the first time likes to try it for a day, of course with the right drinks in the right quantities. Even 24-hour fasting has measurable, positive effects. The usual metabolism changes because no food comes.

“The body first uses up the stored carbohydrates, i.e. glycogen, these reserves last for one to one and a half days,” explains the chief physician. In addition, autophagy comes into play. This is a sophisticated recycling system in the body that frees cells from defects.

Eva Lischka explains: “One can imagine that cellular waste (aged, non-functioning or incorrectly assembled cell components) is surrounded by a shell. Inside, enzymes break up these parts.” The individual components are fed back into the cell and help to rebuild healthy cell components. The body starts this autophagy program after a break from eating for 14 to 18 hours, which is definitely after a day of fasting. Incidentally, in 2016 the Japanese researcher Yoshinori Ohsumi received a Nobel Prize for work on autophagy.

Periodic fasting such as therapeutic fasting for one to three weeks not only gets these processes going over a longer period of time – a corrective for the entire body, comparable and simplified with a “major cleaning”. In addition, the entire metabolism changes.

What that means: If the food break lasts longer, glycogen, i.e. sugar, which is urgently needed by the brain, is used up. Now the body can produce sugar from certain proteins. It succeeds in doing this primarily from the supporting protein (connective tissue) in overweight people and to a lesser extent from muscle protein.

However, the sources are limited, not all protein may be used up. Therefore, the organism falls back on fat reserves. “Fat consists of glycerol, which can also be converted into sugar, and fatty acids,” the expert explains the underlying mechanism. The fatty acids are broken down into ketones, which the brain can use to serve its energy metabolism – instead of sugar.

“In the process, the inner abdominal fat is broken down first,” says Eva Lischka. This is particularly beneficial because this fat depot produces, among other things, more than 600 messenger substances that can be associated with metabolic disorders such as diabetes, inflammation and cardiovascular diseases.

The body’s fat reserves last for many weeks in most people. “A healthy man who weighs 70 kilograms and is 1.70 meters tall can fast for 40 days without any problems, that’s scientifically proven,” reports the therapeutic fasting expert. If the man weighed 90 kilograms, he would even have reserves for 100 days. During this time, the whole body is fundamentally cleaned, so to speak.

Dangerous side effects do not usually occur even during this “biblically” long fasting period. To be on the safe side, however, patients who are fasting for several weeks in the clinic have their sodium and potassium blood tested after three weeks to ensure that no mineral deficiency affects the organ functions. An EKG is also taken to check the heart rhythm.

The fear that fasting will break down muscles (protein) is usually unfounded. The organism has, so to speak, a natural brake that protects muscle protein resources. Speaking of muscles. Many fasting people report that their physical performance increases and muscles even continue to build. Studies at the beginning of the millennium have already proven this effect.

With a week of therapeutic fasting, an average of two kilograms can be lost. The decisive factor for health, however, is the waist circumference, the expert emphasizes, because it provides information about the risky inner abdominal fat. A single day of fasting can already cause one to two centimeters. The limit for an unhealthy waist circumference is 80 centimeters for women and 94 centimeters for men. Lying underneath is ideal.

Other effects on the organism:

“A very special effect, however, is that new stem cells are formed during fasting,” reports Eva Lischka. In addition, new mitochondria, i.e. power centers of the cells, are created. This biochemical process is called mitohormesis. When fasting, old mitochondria are thrown away and this deficiency triggers mitohormesis.

Therefore, fasting and calorie reduction is life-prolonging, which numerous studies have already proven.

In the beginning, fasting means a certain amount of stress for the body, the sympathetic nervous system is activated because survival is at stake. But after two or three days, the parasympathetic kicks in. That means mental calm, relaxation, balance. In addition, dopamine and serotonin are now more effective, which makes us happy and curbs our appetite. This is also the reason why hunger during the fasting cure is usually only a problem on the first day – which can, however, be remedied with a lot of drinking and a spoonful of honey.

Last but not least, the body’s own endocannabinoids are strengthened, which also balances and improves mood. The often-cited fasting euphoria is said to be triggered by all of these factors – it can, but does not have to be clearly pronounced in every fasting person.

For mental and physical health, not eating means much more than you might think. Fasting is therefore also recognized for many different diseases as a therapy or as an adjunct to treatment. A study in the specialist journal “Plos One”, for example, has shown how well therapeutic fasting works.

According to this, diabetes improves significantly under fasting. “Receptors that are important in diabetes become sensitive again through fasting,” explains the expert. In diabetics, the insulin receptors are often blocked by fatty acids (insulin resistance), the sugar can no longer get into the cells. The pancreas therefore produces even more insulin, the insulin level rises and diabetes develops.

“Many diabetics do not need any medication during the fast and even less of it after the fast because the receptors work better again – and because the patients are more open to a lifestyle change with exercise and a conscious diet after the cure,” explains Eva Lischka.

Just in December, a new study published in the Journal of Clinical Endocrinology and Metabolism found that fasting normalized blood sugar levels in more than half of people with diabetes.

It has been proven that hypertensive people also benefit from therapeutic fasting. Fasting affects certain substances called natriuretic peptides. They ensure that water is excreted and fat is burned. “Researchers were able to prove that fasting improves these activities,” explains Eva Lischka. Especially at the beginning of fasting, a lot of water and salt are excreted, which lowers blood pressure.

Incidentally, this effect has been proven to last somewhat after the fasting cure. It also plays a role here that the patients do not weigh as much after the treatment as they did at the beginning. Every kilogram less can lower blood pressure in overweight hypertensive patients.

Diseases that are kept going by silent inflammation, such as rheumatism, arthritis, irritable bowel syndrome, but also migraines, respond well to fasting. “Fasting has an anti-inflammatory effect,” says the expert. Because every meal is an external contact for the body, triggers inflammatory reactions (postprandial leukocytosis and start of the Nuclear Factor kappa B (NF-kB) – inflammatory signaling pathway. This in turn can support existing inflammations. If there is no contact with external food, the body is spared and additionally relieved of digestive work.

The question remains whether therapeutic fasting could also reduce the risk of cancer or improve the prognosis in the event of illness. “The studies are still ongoing here,” says the expert, putting the brakes on excessive expectations. However, it is now considered certain that it is beneficial not to feed the tumor with sugar during chemotherapy. Then the tumor is more sensitive to the chemotherapy and the patient also tolerates the treatment better.

This therapeutic effect of fasting continues in many patients for months afterwards. The same goes for weight maintenance. On the subject of the yo-yo effect, the nutritionist Françoise Wilhelmi de Toledo conducted a study at the clinic with 400 patients who completed around ten fasting cures over a period of ten years. The result:

So two-thirds were quite successful. “In our clinic, we have had the experience that these effects last around six months in our severely overweight patients, so it makes sense to fast again for at least ten days – including rest days and slowly returning to normal eating,” reports die Chief Physician.

For some people, however, it has also proven useful to fast one day a week afterwards or to do 16:8 intermittent fasting, i.e. either without breakfast or without dinner. In this way, obesity and metabolic changes can be prevented and obesity prevented.

In principle, almost anyone can do fasting as a form of prevention and therapy, but there are exceptions. The following are contraindications for fasting:

Depending on the type of pill, women who use the pill should also use condoms during and after fasting. The effect of the pill is not certain during fasting because absorption may not be complete, as with diarrhea

“Anyone who takes medication may only fast under medical supervision,” adds Eva Lischka. There are trained fasting doctors and fasting leaders at:

So almost everyone can fast and everyone can benefit from it. However, there may be a downside to fasting. Many toxins from our environment are stored in adipose tissue. When you lose weight, they are released and get into the blood, could put a strain on the liver and kidneys. “It’s true, studies show that toxins from fatty tissue get into the blood when fasting, but we don’t know whether they are finally being disposed of and the body is being rid of these substances,” reports Eva Lischka. This has not yet been sufficiently studied.

On the other hand, what is known for sure is that losing weight gets rid of dangerous visceral fat. Three quarters of men and more than half of women have too much of it. This belly fat is so risky because it triggers silent inflammation. These “silent inflammations” are significantly involved in the main causes of death, heart attack, stroke and sometimes also cancer. Without belly fat, the risk of these causes of death also decreases. This is another reason why fasting can prolong life.

“As long as studies have not proven otherwise, we should therefore rely on our experience,” emphasizes the chief physician. She treats many patients who have been fasting for decades and who have been able to improve their chronic diseases, and who often appear biologically much younger. If the toxin exposure from fasting was really pronounced, it would have been noticed.

And what must not be forgotten: “Unhealthy eating and drinking puts much more strain on the liver and kidneys than fasting.” Every food intake is contact with foreign substances and triggers a slight inflammatory reaction, not to forget the pollutants and toxins in our diet Pesticides, pollutants, microplastics and more.

Fasting is undisputedly a proven and simple method not only to get rid of dangerous belly fat, but also to regenerate and, so to speak, rejuvenate the organism as a whole. It is not only recommended for healthy people, but can also supplement or even replace therapy for many diseases, such as type 2 diabetes, but in any case alleviate and prevent common diseases such as obesity, high blood pressure, arteriosclerosis and joint inflammation.