Fasting and Weight: What Is Realistic

Key takeaways

• Buchinger therapeutic fasting is neither a zero-calorie diet nor a primary weight-loss method, but a therapeutic method — weight loss is a side effect, not the purpose.
• Two processes run at the same time in the body: the switch to fat burning and autophagy, the cellular recycling. The two should be kept distinct.
• Part of the early drop in weight is water, part is fat reserves — how much is individual and depends on duration and starting point.
• Without a follow-up strategy, weight often returns after short diets; the effect lasts only with a change in eating habits.
• At the Tannerhof, the closing consultation with the accompanying physicians discusses what continues in everyday life — Schlanke Tanne Low Carb or intermittent fasting.

Why weight is the wrong guiding question when fasting

Buchinger therapeutic fasting is the conscious, time-limited abstention from solid food and stimulants. That weight falls in the process is obvious and true — yet that number on the scale says little about what fasting is actually for. Buchinger 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 comes along, not the goal to which everything is subordinated.

This distinction carries the whole article. Anyone who fasts to reach a particular number measures fasting against something it never promised. Anyone who fasts to unburden the body, to set a caesura and to rediscover their own eating rhythm experiences the drop in weight as the by-product of a deeper change. This is exactly how fasting is intended at Naturhotel Tannerhof, and exactly how the medical team accompanies it. To see the setting at the house, look at the Body Detox programme; the method itself is described on the page about the Buchinger method.

Two sentences still shape the house's stance today. Otto Buchinger's fasting stimulates the inner physician and the handed-down words of Johannes von Mengershausen, who brought therapeutic fasting to the Tannerhof: In fasting you discover a new freedom: independence from solid food. Fasting means stillness, listening to what happens within, and reflection on what is essential. In neither does weight stand in the foreground — and yet the body changes.

What happens in the body: two processes at once

To understand why weight falls, it helps to look at the two levels on which the body works during fasting. They are often conflated and should be clearly separated.

The first level is fat burning. As the quickly available carbohydrate stores decline, the metabolism switches within the first one to three days from glucose to fatty acids and ketone bodies. Researchers Rafael de Cabo and Mark Mattson describe this change as a metabolic switch in their 2019 review in the New England Journal of Medicine: the body increasingly meets its energy needs from its own fat reserves rather than from ingested carbohydrates. This is the energetic side of fasting and the actual reason fat mass is broken down.

The second level is autophagy. It refers not to fat burning but to the body's own recycling and cleansing processes at the cellular level: cell components are broken down, reused and reorganised. Put more vividly — every recycling process is set in motion, and cleaning happens everywhere: in the cells, the vessels, the connective tissue, the gut, the brain, the liver and the kidneys. This level has nothing to do with the scale and is nonetheless the real aim of fasting.

Both processes occur together but describe different mechanisms. Anyone who looks only at weight sees only half the story of these two levels — and misses that the level more interesting for health is the one that cannot be weighed.

How much is really fat?

An honest assessment belongs here: not every kilogram that disappears in the first fasting days is fat. At the start the body also loses water, because the carbohydrate stores in muscle and liver are emptied and release the water bound to them. Only over the days does the breakdown of fat reserves gain a larger share. How much of the change in weight is ultimately fat and how much is water is individual and depends on duration, starting point and metabolism.

This is precisely where bioimpedance analysis comes in at the Tannerhof. It is part of the medical examination and measures body composition — the proportion of water, muscle mass and fat. It allows the course of a fasting week to be described factually, beyond the bare number on the scale. This measurement makes visible what is actually happening, instead of letting a figure in kilograms speak for itself.

How the muscles are handled matters too. So that the body draws mainly on its fat reserves during fasting and largely spares muscle mass, movement and a moderate protein intake are part of it. At the Tannerhof, a freshly pressed juice with either buttermilk or Sojade, further protein sources where needed, plus moderate base endurance training and moderate strength training all help fasting to remodel the body rather than merely make it lighter.

Why one week alone is not enough

This is the decisive point for everyone hoping for a lasting change in weight from fasting. A fasting week can be a wonderful beginning, but it is not a result that holds on its own. The German Nutrition Society (DGE) describes the pattern of short diets clearly: 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, a lasting change in weight succeeds only through a combination of changed eating habits, behavioural change and more movement.

That is exactly why therapeutic fasting at the Tannerhof is never meant as an isolated week, but as a prelude. In their review, de Cabo and Mattson likewise frame forms of fasting less as a short-term measure than as a metabolic pattern that unfolds its effect through recurring practice. The fasting week flips the switch; whether it stays flipped is decided by what comes afterwards.

This is not a limitation but the real opportunity. A fasting week creates a rare openness to change: taste shifts, the sense of satiety reports more clearly, the joy of eating often returns more intensely. This openness is the best ground for a new eating habit — if it is used, rather than falling back into the old rhythm after the refeeding phase.

Refeeding as the bridge into everyday life

Refeeding is not a postscript to fasting but its continuation by other means. It begins with breaking the fast, which still counts as part of the fasting period: a small cup of fasting soup at midday, then the apple, raw or steamed, each bite chewed thirty to forty times. After that comes the build-up over roughly a third of the fasting period — a gradual return to solid food and stimulants.

At the centre stands not a complicated meal plan but a guiding question: what is good for the microbiome? Easily digestible vegetables, fermented foods, plenty of fibre and mindful chewing, with respect for the sense of satiety. Anyone who takes refeeding seriously extends the effect of fasting into the first everyday days — and that is precisely the point of this phase. It is the bridge between the caesura of fasting and the question of how things continue.

What carries the effect for the long term

In the closing consultation with the accompanying physicians, what has changed is reviewed, and how the transition into eating afterwards might look is discussed. This is where it is decided whether a fasting week becomes a lasting change. Two paths have proven themselves at the Tannerhof.

The first is Schlanke Tanne Low Carb, the house's own low-carb way of eating. It is not a substitute for Buchinger fasting but a way of eating differently in everyday life — with protein, vegetables, good fats and the aim of eating differently again without diminishing the joy of eating. When, instead of going without, the gain in enjoyment and zest for life takes centre stage. Anyone seeking a sustainable change after fasting finds in it a continuation that carries the metabolic shift of the fasting week into everyday life. The hub Therapeutic Fasting and Schlanke Tanne Low Carb gives an overview.

The second path is intermittent fasting, for instance in a 16/8 rhythm. It too is not a substitute for Buchinger fasting but the recommended way to carry the benefits of compact fasting into everyday life. Anyone who regularly lets a longer eating window rest keeps the metabolic switch the fasting week flipped in motion again and again — without having to set aside a whole week each time. Schlanke Tanne Intervall can be one Tannerhof route for this. Which follow-up nutrition fits in an individual case belongs not in a general formula but in the closing consultation with the accompanying physicians.

In this way a fasting week becomes more than a brief abstention. It gains a beginning, a middle and a transition — and the weight that has changed does not remain a fleeting number but becomes part of a new way of living. Perhaps that is exactly the old Tannerhof motto in present-day form: become essential.

Fasting and movement at the Tannerhof

The accompanying offering is deliberately broad, because fasting is more than a change of diet for a few days. The medical core consists of the medical history and examination, the medical follow-up consultation and the closing consultation, the bioimpedance analysis to measure body composition and, depending on the programme, IHHT altitude training. Added to this are compresses and wraps such as the liver-supporting hay-flower wrap, the aroma wrap as well as mud and warm packs, baths and affusions such as the Kneipp alternating affusion and magnesium-rich detox baths, plus massages such as the fasting massage, the detox massage with King's Oil or the acidosis massage, lymphatic drainage and breathing therapy. For the mental side, there is psychotherapeutic coaching, nature coaching and art therapy.

Movement remains part of fasting, moderately dosed, and it is what helps the body to draw mainly on its fat reserves. Moderate base endurance training and moderate strength training are available, as are yoga, Feldenkrais, Tai Chi and resistance-band training. Summit hikes and running are possible, only at a pace that suits fasting — the body nourishes itself from within. Above it all lies the place: Bayrischzell, the alpine meadow, the mountain stream, clear and pure mountain air and the view to the Wendelstein. My hideaway in the mountains is the quiet setting in which fasting and medical care reinforce one another. What happens in the body's cleansing beyond the fasting week is described on the page about Body Detox and detoxification.

Discover therapeutic fasting at the Tannerhof

Naturhotel Tannerhof has accompanied Buchinger therapeutic fasting with medical care for over 70 years — set in Bayrischzell, between alpine meadow, mountain stream and the view to the Wendelstein. To see the concrete setting and book online, look at the Body Detox programme and the page about the Buchinger method. The hub Therapeutic Fasting and Schlanke Tanne Low Carb gives an overview of therapeutic fasting and Schlanke Tanne Low Carb, the house's own low-carb way of eating.