Fasting is not a modern invention – it is an ancient ritual deeply rooted in human history. Even our Stone Age ancestors were involuntary fasters when food was scarce. This periodic lack of food has shaped our survival and significantly influenced our metabolism. With the emergence of advanced civilizations, fasting then became consciously practiced – often as a cleansing or spiritual ritual.
In ancient Greece, philosophers like Pythagoras fasted to gain clarity and mental strength. In the Middle Ages, fasting was an integral part of the Christian calendar, especially during Lent before Easter. Fasting also has central importance in other religions: In Islam, fasting is observed during the holy month of Ramadan from sunrise to sunset to spiritually cleanse and develop compassion for the needy. Buddhists and Hindus use fasting to promote discipline and meditation, while in Judaism, Yom Kippur – the Day of Atonement – is marked by fasting.
But what does this ancient ritual have to do with modern science? In recent decades, research has looked at fasting from a new perspective. It is no longer seen just as a religious or cultural phenomenon, but as a potential tool for promoting health and longevity. What effects does fasting really have on our body? And how can we integrate this ancient practice into our modern lifestyle?
What Happens in Our Body During Fasting?
As soon as we go without food for an extended period, our body goes through several metabolic phases and changes its energy production:
- Glycogen stores deplete: In the first hours after the last meal, the body taps into stored carbohydrates in the form of glycogen in the liver and muscles. These reserves usually last for about 12 to 24 hours.
- Fat burning and ketosis: Once glycogen stores are exhausted, the body begins to convert fat into so-called ketone bodies, which serve as an alternative energy source for the brain and muscles. This state is known as ketosis and is one of the main reasons why fasting can have so many positive effects on the body.
- Autophagy: After about 16 to 24 hours without food, a process called autophagy begins. This is a cellular cleaning process where old or damaged cell components are broken down and recycled. This phase of fasting is particularly associated with health-promoting effects.
Scientifically Proven Benefits of Fasting
The health effects of fasting are diverse and well-documented:
- Weight reduction: Fasting, especially intermittent fasting, can effectively help reduce excess weight. Fat deposits are specifically broken down through fat burning.
- Improved insulin sensitivity: Regular fasting periods can improve insulin effectiveness and thus reduce the risk of type 2 diabetes
- Reduction of inflammation: Fasting has an anti-inflammatory effect, which can be beneficial for chronic diseases such as rheumatism or heart diseases.
- Anti-aging effects: Autophagy supports cell regeneration and is associated with a slowed aging process.
- Improved brain function: Studies show that fasting promotes the production of BDNF (brain-derived neurotrophic factor), a protein essential for the formation of new nerve cells and cognitive health.
What Types of Fasting Are There?
Not all fasting is the same. There are different approaches that vary in duration and intensity:
- Intermittent fasting: This involves alternating between eating and fasting periods, for example, the 16:8 model (16 hours fasting, 8 hours eating time).
- Therapeutic fasting: This method involves multi-day fasting periods, often under medical supervision. Only liquids such as water, tea, or clear broths are consumed.
- Religious fasting: Examples include Muslim Ramadan or Christian fasting before Easter, where abstaining from food is often combined with spiritual practices.
Who Should Not Fast?
As healthy as fasting can be, it’s not suitable for everyone. Pregnant women, nursing mothers, children, people with eating disorders or certain chronic illnesses should not fast or should only do so under medical supervision. Fasting can also be problematic for those with severe underweight, advanced diabetes, certain thyroid conditions, or those taking certain medications.
Practical Tips for a Successful Start to Fasting
- Hydration: Drink plenty of water to avoid dehydration.
- Start slowly: Begin with short fasting periods and gradually increase the duration.
- Don't overdo it: Fasting is not a substitute for a balanced diet. Make sure to consume nutrient-rich foods during eating phases.
- Exercise: Light exercise such as walking or yoga supports metabolism during fasting.
Fasting as a Lifestyle
Fasting is much more than a short-term nutritional trend. It can contribute to a holistic improvement in health, from cell renewal to cognitive performance. However, it’s important to listen to your own body and find the method that best suits your individual needs. Feel free to consult with me at my practice to find out how fasting can support your health goals.