Fasting and muscle protein: The top 4 takeaways

Written By Tina O

Is muscle and protein loss relevant in long term fasting? 

In this video Dr. Franciose de Toledo discuses the results of a published study by the Buchinger Clinic of 16 healthy men during a long term water fast.


This article is for athletes and anyone who is concerned about losing precious muscle during fasting. It is a summary of the video by the same title from the Buchinger Clinic on the results of a recent study. 

Top 4 takeaways:

  1. We can fast, get all the amazing health benefits fasting provides, and yet keep or even improve our physical performance! This is better than having our cake and eating it too. 😊
  2. In this 10 day study of healthy men, results showed that leg strength increased! Speed in climbing stairs increased.  All muscle parameters measured either increased or stayed the same.  Such good news for those of us who worried that fasting might damage muscle.
  3. During fasting, the epigenetic switch leads to mitochondrial and cell repair, reduction of anti inflammatory reactions, anti-oxidation, as well as enhancement of mood and cognitive behavior.
  4. In addition to the physical benefits, they found emotional well-being increased too!


What is the Buchinger Clinic?

  • The Buchinger Clinic started  70 years ago and specializes in therapeutic, long term fasting. The clinic now treats over 6,000 patients a year for various conditions such as chronic inflammatory diseases, mood disorders, etc. 
  • The Clinic has fought for a long time against the notion that fasting is only beneficial for overweight and obese people and that with fasting there is a danger in losing protein and muscle (this is a dogma)

How long can you live without food?

  •    1970 Cahill study labeled “Starvation in Man“ shows: A person of normal weight  has enough reserves for 40 days of fasting. This is from (average) reserves of 10 kg fat, 3 kg recycled proteins and .75 kg glycogen.

What happens to our bodies while fasting?

  • Thanks to ‘sciences of longevity’ we now know fasting is not only to lose weight, but also has many other healthy benefits.
  • During fasting, the epigenetic switch leads to mitochondrial and cell repair, reduction of inflammatory reactions, anti-oxidation, as well as enhancement of mood and cognitive behavior.
  • Other metabolically active tissues participate more than muscle in fasting protein utilization. In mice during fasting all the organs shrink. These same organs rebuild when food is re-introduced.
  • During fasting, the brain and the testes did not shrink and the muscles were preserved. Evolutionarily this makes sense. During the predatory times when we needed food we needed our brain to think and muscles to chase/gather food. Also there is always a strong need to procreate.

What new information did we learn in this latest study from the clinic?  

  • In the Buchinger clinics’ latest study (0ct 2021) 16 healthy men of normal weight to light overweight showed what happens in the muscle reserves and performance during 10 days of Buchinger Wilhelmi fasting with 250 cals a day, mild exercise including mild gymnastics. The  results show measurements taken at baseline, after 4 days of fasting, after 9 days of fasting, day 4 of food reintroduction, and a 3 month follow up.
    • The metabolic switch was confirmed (glucose goes down, insulin drops, non-esterified fatty acids increase, Igf-1 increased).
    • A 6kg weight loss mainly in abdomen.
  • The weight loss of 6 kilos was analyzed: 40% from fat, 40-60 % from metabolically active tissue, water bound to glycogen  and extra cellular water.
  •  The study does show some proteolysis in the very beginning. However this is very short term. Once the body is into ketosis then a decrease in proteolysis occurs. 
  • Leg strength was measured and showed an increase! 
  • Speed to climb stairs increased.  None of the measured muscle parameters diminished. 
  • Inflammatory parameters diminished. 
  • Already healthy men still showed an increase in their physical and emotional well being.
  • Cortisol went down and stayed down during refeeding. The lowered cortisol may be because at the clinic patients are well taken care of.
  • Proper reintroduction of food  is very important to keep the beneficial anti-inflammatory markers down.


This video is well worth one’s time to watch especially if you’re thinking about starting your own fasting program.  Your body will thank you!


For those who enjoy Dr. Francoise’s research, here’s a few additional links to her other videos:


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