Therapeutic Fasting and Weight: What is Realistic

The essentials at a glance

• Buchinger therapeutic fasting is not a crash diet or a primary weight-loss method, but a therapeutic approach — weight loss is a side effect, not the purpose.
• Two processes occur simultaneously in the body: the switch to fat burning and autophagy, or cellular recycling. It is important to distinguish between the two.
• Part of the initial weight loss is water, and part is fat reserves — the exact amount is individual and depends on the duration and your starting point.
• Without a follow-up strategy, weight often returns after short diets; only a change in diet provides lasting results.
• At the Tannerhof, the final consultation with our doctors covers what comes next in your daily life — whether that’s our "Schlanke Tanne" low-carb approach or intermittent fasting.

Why weight is the wrong metric when fasting

Buchinger therapeutic fasting is the conscious, time-limited abstinence from solid food and stimulants. It is true that weight drops during this process — but the number on the scale tells us little about what fasting is actually about. Buchinger therapeutic fasting is more than a diet: it is a therapeutic method, a cleansing on many levels, and an encounter with oneself. Weight loss is a side effect that happens along the way, not the goal to which everything else is subordinated.

This distinction underpins the entire article. Those who fast to reach a certain number are measuring fasting by something it never promises. Those who fast to lighten the load, make a clean break, and rediscover their natural rhythm of eating will experience weight loss as a byproduct of a deeper transformation. That is precisely what therapeutic fasting at Naturhotel Tannerhof is designed to do, and precisely how our medical team guides you through it. If you would like to explore the retreat's setting, you will find it in the Body Detox program; the methodology itself is detailed on the page about the Buchinger method.

Two principles have shaped our approach to this day. Otto Buchinger’s belief that fasting activates the inner physician, and the timeless words of Johannes von Mengershausen, who introduced therapeutic fasting to the Tannerhof: During therapeutic fasting, you discover a new freedom: independence from solid food. Fasting means stillness, listening to what is happening within, and reflecting on what truly matters. Neither focuses on weight — and yet the body transforms.

What happens in the body: two processes at once

To understand why weight drops, it helps to look at the two levels on which the body works during a fast. They are often confused and should be clearly separated.

The first phase is fat burning. As rapidly accessible carbohydrate stores dwindle, the metabolism shifts within the first one to three days from glucose to fatty acids and ketone bodies. In their 2019 review published in the New England Journal of Medicine, researchers Rafael de Cabo and Mark Mattson describe this transition as a metabolic switch: the body increasingly meets its energy needs from its own fat stores rather than from dietary carbohydrates. This is the energetic aspect of fasting and the true reason fat mass decreases.

The second level is autophagy. This does not refer to fat burning, but to the body’s own recycling and cleansing processes at the cellular level: cell components are broken down, utilized, and reorganized. To put it more elegantly — all recycling processes are activated, and a thorough cleaning takes place everywhere: cellularly, vascularly, in the connective tissue, in the gut, in the brain, and in the liver and kidneys. This level has nothing to do with the scale, yet it is the true goal of fasting.

Both processes occur together, but they describe different mechanisms. Anyone who only looks at the weight sees only half the story — and overlooks the fact that the level most interesting for your health is the one that cannot be weighed.

How much is actually fat?

It is important to be honest: not every kilogram lost in the first few days of fasting is fat. Initially, the body also loses water because carbohydrate stores in the muscles and liver are depleted, releasing bound water in the process. It is only over the course of several days that the breakdown of fat reserves becomes more significant. How much of the weight change is ultimately fat and how much is water is individual and depends on the duration, starting point, and metabolism.

This is exactly where bioelectrical impedance analysis comes in at the Tannerhof. It is part of the medical examination and measures body composition—the proportions of water, muscle mass, and fat. This allows the progress of a fasting week to be described objectively, beyond just the number on the scale. This measurement makes it clear what is actually happening, rather than letting a weight figure speak for itself.

Managing muscle mass is also important. To ensure the body primarily targets fat reserves during fasting while largely preserving muscle mass, physical activity and a moderate intake of protein are essential. At the Tannerhof, a freshly pressed juice with a choice of buttermilk or soy milk, additional protein sources if needed, as well as moderate endurance and strength training, help ensure that fasting reshapes the body rather than just making it lighter.

Why one week alone is not enough

This is the crucial point for anyone hoping for a lasting change in weight through fasting. A fasting week can be a wonderful start, but it is not a result that maintains itself. The German Nutrition Society (DGE) clearly describes the pattern of short-term diets: those who lose a lot of weight quickly often regain it just as quickly after the diet—sometimes even more than before. According to the DGE, lasting weight change is only successful through a combination of dietary adjustments, behavioral changes, and more physical activity.

This is precisely why therapeutic fasting at the Tannerhof is never intended as an isolated week, but as a starting point. In their overview, de Cabo and Mattson also classify fasting forms less as a short-term measure and more as a metabolic pattern that unfolds its effect through recurring practice. The fasting week flips the switch; what happens afterward determines whether it stays flipped.

This is not a restriction, but the real opportunity. A fasting week creates a rare openness to change: your sense of taste changes, your feeling of satiety becomes clearer, and the joy of eating often returns more intensely. This openness is the best foundation for a new eating habit—if you use it, rather than falling back into old patterns after the transition phase.

The transition phase as a bridge to everyday life

The transition phase is not an afterthought to fasting, but its continuation by other means. It begins with breaking the fast, which is still considered part of the fasting period: a small cup of fasting soup at noon, then an apple, raw or stewed, with every bite chewed thirty to forty times. This is followed by a transition period lasting about one-third of the fasting time—a gradual reintroduction to solid foods and indulgences.

The focus here is not on a complicated meal plan, but on a guiding question: What is good for the microbiome? Easily digestible vegetables, fermented foods, plenty of fiber, and mindful chewing, while respecting your sense of satiety. Those who take the transition phase seriously extend the effects of fasting into their first days back in everyday life—and that is exactly the purpose of this phase. It is the bridge between the break provided by fasting and the question of what comes next.

What sustains the effect in the long term

In the final consultation with the attending physicians, we evaluate what has changed and discuss what the transition to your subsequent diet can look like. This is where the decision is made as to whether a fasting week becomes a lasting change. Two paths have proven successful at the Tannerhof.

The first path is the Schlanke Tanne Low Carb, our in-house low-carb diet. It is not a substitute for Buchinger fasting, but rather a way of eating differently in everyday life — with protein, vegetables, healthy fats, and the aim of rediscovering a new relationship with food without diminishing the joy of eating. Where pleasure and the joy of living take center stage instead of restriction. For anyone seeking a sustainable transition after fasting, it provides the bridge that carries the metabolic reset of the fasting week into daily life. An overview is available on the Therapeutic Fasting and Schlanke Tanne Low Carb hub.

The second path is intermittent fasting, for example, following a 16:8 rhythm. It is likewise not a replacement for Buchinger fasting, but the recommended way to carry the benefits of immersive fasting into everyday life. By regularly resting for an extended eating window, you keep the metabolic switch that was flipped during the fasting week continuously engaged — without having to set aside an entire week each time. The Schlanke Tanne Intermittent approach offers a Tannerhof path to this. Which follow-up nutritional concept fits your individual needs is not a matter of a one-size-fits-all formula, but of your closing consultation with the supervising physicians.

In this way, a week of fasting becomes far more than a brief period of deprivation. It gains a beginning, a middle, and a transition — and the weight that has shifted is not just a fleeting number, but becomes part of a new way of living. Perhaps that is simply the old Tannerhof motto in modern form: Focus on the essential.

Fasting and movement at the Tannerhof

The accompanying range of services is deliberately broad because fasting is more than just a dietary change for a few days. The medical core consists of the medical history and examination, follow-up medical advice and the final consultation, bioelectrical impedance analysis to measure body composition, and, depending on the program, IHHT altitude training. In addition, there are wraps and compresses such as the liver-supporting hay flower wrap, aroma wraps, as well as mud and warm packs, baths and showers such as the Kneipp alternating shower, and magnesium-rich detox baths. There are also massages such as the fasting massage, the detox massage with royal oil or the acidosis massage, lymphatic drainage, and respiratory therapy. For the mental side, we provide psychotherapeutic coaching, nature coaching, and art therapy.

Physical activity remains an integral part of fasting, tailored in moderate doses, and it is precisely what helps the body tap predominantly into its fat reserves. Gentle baseline endurance training and moderate strength training are available alongside yoga, Feldenkrais, Tai Chi, and resistance-band workouts. Summit hikes and running are possible, but only at a pace suited to fasting — the body is drawing nourishment from within. Above all lies the setting itself: Bayrischzell, the alpine meadows, the mountain stream, clear, pure mountain air, and views stretching toward Mount Wendelstein. My mountain hideaway provides the tranquil sanctuary in which fasting and medical care reinforce each other. What happens during this bodily reset beyond the fasting week is described on the page on Body Detox and Cleansing.

Discover therapeutic fasting at Tannerhof

Naturhotel Tannerhof has provided medically supervised Buchinger therapeutic fasting for over 70 years — nestled in Bayrischzell, between alpine meadows, mountain streams, and views of Mount Wendelstein. If you would like to explore the full details and book online, you will find them in the Body Detox program and on the page dedicated to the Buchinger method. An overview of therapeutic fasting and Schlanke Tanne Low Carb, our signature low-carb nutritional plan, can be found on the Therapeutic Fasting and Schlanke Tanne Low Carb hub.