OUR RECOMMENDATIONS
How long should you fast?
Fasting has many positive effects, stimulating the body’s own recycling programme and causing weight loss leading to visceral fat mass reduction. Fasting can even prevent certain diseases. In our clinics we offer therapeutic fasting based on the method developed by Dr. Otto Buchinger. There is also the option of fasting at home for several days or even overnight. How long a person should fast depends not only on the method used, but also on who is fasting. The length of a fast strongly influences its success and the associated health benefits.
Effects of fasting on the body
Many people fast to change their lifestyle for the better and are often motivated by the desire to lose weight and eat more healthily. But how exactly does fasting work and how long should you fast to lose weight? When you fast, your body is not receiving food, causing the metabolism to change. This can lead to positive effects such as weight loss and the normalization of risk factors for chronic diseases. During fasting, your body undergoes a series of changes to maintain energy.
- In the first few hours (0-4 hours), it uses glucose from your last meal.
- As glucose levels drop between 4-12 hours, the body starts breaking down glycogen, a stored form of glucose in your liver and muscles, to keep your energy levels stable.
- After 12 hours, as glycogen stores diminish, your body begins to create new glucose through a process called gluconeogenesis, using components from muscles, fats and proteins.
- By 24 hours and beyond, your body increasingly turns to fat for energy and your liver will convert these fatty acids into ketones, an alternative energy source that the brain and other organs can use, reducing the need for glucose and helping to preserve muscle tissue. This process ensures that even without food, your body can continue functioning by efficiently using its stored energy reserves.
How long it takes to burn fat
When we fast, our body no longer gets the energy it needs from food in the form of glucose but draws on its stored reserves instead. The metabolism switches to burn mainly fat and ketone bodies. This results in less body fat and a lower overall weight. We have developed an estimator so that you can understand how much body weight you would lose while fasting at our clinics. The body can work perfectly using mostly fat as a source of energy for several days or weeks.
Cell cleansing and regeneration through fasting
Weight loss is just one positive effect associated with fasting. Fasting also triggers cleansing processes that eliminate deformed and damaged cells. One of these processes is called autophagy. It is also an important part of our immune defence and helps to sift out pathogenic germs. This “self-cleansing programme” also takes place in people who are not fasting at a minimal intensity, but abstaining from food boosts the process and intensifies it.
Scientists still don’t know when autophagy is activated during fasting because this is difficult to measure. Studies indicate that it is activated in the first day of the fast but that might depend on individuals. A key molecule in this process is spermidine, which significantly increases during fasting. Spermidine enhances autophagy by promoting a cellular process that is conserved across many species, including humans. A recent study conducted at the Buchinger Wilhelmi clinics has shown that our long-term fasting programme boosts spermidine levels, which in turn activates autophagy. This cellular regeneration process helps protect against aging and disease, highlighting the profound health benefits of fasting.
> Read here how fasting can detoxify the body.
Fasting helps our cells to regenerate. At the same time, fasting brings about anti-inflammatory effects which improve chronic pain and mobility restrictions. Finally, therapeutic fasting helps to regenerate the tissue and organs by activating the stem cells and accelerating protein synthesis when food is reintroduced. These beneficial processes begin as soon as the body starts burning fat instead of glucose. They continue throughout the fast, which is why it is often worth fasting for a long period with a package of 21 or 28 days in order to successfully treat some advanced cases of auto-immune diseases like rheumatoid arthritis. Such a long stay would also make sure that you are having 4 days of food reintroduction which our recent studies showed are key for the regeneration of the body.
Psychological effects of fasting
Fasting also has an impact on our mental state. Long-term fasting can have a soothing and relaxing effect on the psyche. Fasting provides the ideal framework to clear your mind. It is not uncommon for repressed emotions to come to light, which can then be dealt with. This is why we offer psychological support at our clinics. Many people also feel psychologically stronger while and after fasting, with some talking of a fasting “high”. On the other hand, patients tend to feel more confident after doing a longterm fast after experiencing the self-healing power of their own body.
Therapeutic fasting: How long fasting lasts at the clinic
Our founder Dr. Otto Buchinger developed therapeutic fasting more than 100 years ago. We have continuously developed his method ever since and offer long-term fasting in our clinics. Fasting begins with at least one digestive rest day, in which the food intake is reduced. The body takes around two to three days to adapt to the fasting metabolism. Our experienced physicians determine exactly how long people should fast on a case-by-case basis. Factors such as the patient’s state of health and age play an important role. As a rough estimate, a healthy person can fast for up to 40 days and even longer.
At our fasting clinics, the minimum length of a fasting stay is eleven days (or ten nights), including a digestive rest day and time to reintroduce food after fasting. After all, it is important to eat the right ingredients after fasting to feel the positive effects in the long term and to make sure the digestive system starts working properly again.
When it comes to deciding how long to fast, it is essential that the body and mind are given sufficient time to recuperate. This is particularly relevant in the case of exhaustion or certain physical complaints.
Many of our patients come to our clinic seeking to regenerate from the effects of a stressful life or to invest in their longevity capital. Fasting is one of the most powerful tools in your prevention toolkit, offering profound benefits for both body and mind. To help you discover the benefits of fasting, we offer a 10-day package, which provides an excellent introduction. However, we generally recommend our 14-day package for the full experience, including a transition day and several days of food reintroduction, ensuring that you return to your daily life fully regenerated.
It’s important to note that the first days of fasting can bring some temporary symptoms as your body adjusts to the metabolic switch—such as low energy levels or headaches—but these symptoms typically disappear quickly. We recommend fasting for at least 7 days to move past this adaptation phase and fully experience the long-term benefits of fasting.
Long-term fasting only under medical supervision
We do not recommend fasting for a longer period on your own, especially if it is your first time. If you want to try out fasting at home, there are various options to choose from, which we will discuss later. Patients at our clinics are given medical care around the clock. That way, we can ensure that fasting has the desired effect and that each patient gets the best possible care. We also offer guests a varied programme during their stay, from sporting activities to physical treatments, as well as art and music. Because fasting in a community is easier and more invigorating than doing it alone.
Incidentally, if you cannot fast for health reasons or a lack of time, you can also take advantage of other programmes we offer, such as a calorie-restricted diet or intermittent fasting with light, organic wholefoods. These options are also available for longer stays.
Can you fast for too long?
As with all good things, fasting can also be overdone. Fasting for too long can incur health risks especially if this is not medically supervised. This is why you should consult a trained physician and seek individual advice, especially before starting a long-term fast. At Buchinger Wilhelmi we always start with a thorough health check. If you are unsure whether fasting is right for you, you can contact us directly. For example, if you have an eating disorder or are clearly underweight, we advise against fasting.
It is very important to differentiate between fasting and starving. Your body can fast for up to approximately 40 days and live off its own reserves. Only when the fat reserves are depleted does the body start burning proteins. You should stop fasting before this happens. In most cases we recommend you fast for between five and 30 days, depending on your needs.
Make sure you pay attention to your body’s signals while you fast. At our clinics, professional medical staff are available around the clock to answer any questions or concerns you may have. While some physical symptoms (such as headaches in the first few days) are normal and will subside, you should seek medical advice and support if you have other complaints.
How long you should fast at home
If you do not want to try long-term fasting in a clinic (yet), you can also experience fasting in a reduced form at home. There are various forms of fasting with different effects that we can recommend. We have summed up our assessment for you considering different fasting types here.
Intermittent fasting for several hours a day
Intermittent fasting is a form of fasting in which you abstain from eating food overnight or for several days. As we automatically fast at night, it makes sense to fast intermittently around your normal sleeping time. This might mean not eating for several hours before going to bed or after waking up. We recommend fasting for around ten to twelve hours if your weight is normal, and for 14 to 16 hours if you are overweight. Intermittent fasting can be repeated every day and can therefore be ideally integrated into your routine.
The FASTING BOX: A five-day programme
We have developed our FASTING BOX in response to our guests who ask for a programme to do at home in-between their stays at Buchinger Wilhelmi. The programme lasts five days and begins with a digestive rest day, as at our clinics. The daily calorie intake is higher than if you were fasting at the clinic to enable you to easily manage everyday tasks. Nevertheless, the body can switch to a fat metabolism, with all its positive effects, after two to three days. This option is also suitable for beginners who want to experience the benefits of fasting for the first time and are not yet ready to fast for longer.
We recommend fasting regularly
Therapeutic fasting is the ideal way to adopt a healthier lifestyle. Many of our guests tell us that they were able to keep up their healthy eating habits for several months after fasting. However, after a while most people fall back into old patterns, which is all too understandable, especially in our stressful everyday lives. To get back into healthier habits, you can fast again. Of course, guests who find it easier to live healthily can also benefit from fasting regularly.
Although how often and long you fast, is an individual matter, we recommend the following:
- Fast once a year for a longer period of five to 30 days
- Treat your body to a small reset ideally every two to six months, depending on your individual goals, with our FASTING BOX
- Fast intermittently every day overnight for at least 10-12 hours, ideally 16 hours
These three methods can be combined and supplement each other perfectly. Maybe you can start with intermittent fasting and work your way up to the FASTING BOX. If it feels good, then you might also be interested in long-term fasting.
