Fasting myths uncovered: what is really true?

Fasting is said to be healthy – but does it automatically mean deprivation and suffering? We take a closer look at common fasting myths and reveal what really lies behind them.

Fasting has a long tradition, deeply rooted in many cultures, and in recent years has seen a remarkable revival thanks to its proven health benefits. 
As early as around 400 BC, Hippocrates of Kos described the therapeutic effects of fasting. A little over 100 years ago, important milestones in fasting were set in Europe, leading to the development of different methods over time: from strict water fasting to juice fasting and alkaline fasting. In addition, various accompanying practices were introduced to enhance the effects of fasting or to better support the body in eliminating toxins. 
Over the past ten years, research on fasting has expanded significantly – not only to better understand and optimize its benefits, but also to critically examine well-meant practices that may be less effective or even counterproductive. 
The beginning of the fasting season is the perfect moment to take a closer look at some of the most common myths surrounding fasting.

Your medical & dietitian team at Marienkron

Myth 1 – Fasting means suffering! 
 

False! 
 

The Medical Society for Fasting and Nutrition defines an important criterion: fasting should always go hand in hand with well-being and performance – and of course without any negative health effects. The first 48 hours can be a little bumpy, especially if you have little or no fasting experience. During this time, headaches or mild dizziness may occur – but not necessarily! One reason is the so-called metabolic switch: the body shifts from glucose metabolism to fat burning and begins producing health-promoting ketone bodies. After this adjustment phase, most people feel very well, are physically active, and some even report experiencing a “fasting high.” Still, many people fear they will feel constantly hungry or lack energy and be confined to bed during a fast. This is not the case – provided a few simple but essential points are observed:

Medication: Certain medications can negatively affect fasting or cause serious side effects. Some drugs need to be reduced, regularly adjusted, or even discontinued during fasting – this includes common blood pressure medications or diabetes treatments. There are also substances for which fasting is not recommended at all. IMPORTANT: Even with widely prescribed contraceptives, changes in effectiveness are possible and should be clarified. For anyone taking medication, fasting should always take place under medical supervision.

Medical conditions: Some illnesses may increase side effects during fasting or even make fasting unsuitable. Examples include gallstones (biliary colic) or eating disorders (including past history). A thorough initial consultation is essential to clarify whether closer supervision is needed or whether fasting should be avoided altogether. Certain lab findings can also give indications of possible side effects – or show where fasting could actually be preventive.

Zero diet: Pure water or tea fasting (sometimes with clear broth) is problematic in several respects: the body uses muscle tissue for energy and receives very few essential minerals.

Laxatives: Using laxatives can lead to a loss of fluids and important minerals, which may cause circulatory problems. For the fasting effect itself, neither bowel emptying nor colon cleansing is required.

Activity: Some people want to push themselves to the maximum during fasting days and overload their bodies without planning for recovery phases. As so often in life, the golden rule applies: exertion without overexertion.

Duration: The optimal fasting duration should always be determined individually, depending on physical reserves, pre-existing conditions, and fasting goals. One thing is clear: the right fasting duration is more important than the longest possible fasting duration.

Myth 2 – The gut has to be “clean”

Laxatives, enemas, and flushes for better fasting success and detoxification

False!

Our gut and its microbiota are a true wonder of nature – and they deserve proper care both in everyday life and during fasting. A healthy lifestyle without nicotine and with sufficient physical activity plays an additional, decisive role. The digestive tract functions best when two basic conditions are met: paying attention to what and when we eat and drink, and allowing rest. This means mindful eating without hurry or distraction, but also letting the gut itself rest.

During fasting, the gut microbiome naturally changes – this is often referred to as a “gut reset.” Positive effects include an increase in bacterial diversity and the growth of colonies that produce more protective compounds and health-promoting short-chain fatty acids. None of this requires interventions from above or below.

Today we know that “detox” during fasting must be understood differently. Since the groundbreaking research of aging expert Valter Longo, we’ve learned that many of the key benefits of fasting happen directly inside our cells – such as the phenomenal recycling process called autophagy or the activation of specific genes. Laxatives were never part of his studies, and yet the positive results were fully present. As long as liver and kidney function is intact, these organs reliably take care of metabolism and the elimination of harmful substances.

While laxatives and enemas are part of some fasting traditions – intended to reduce hunger or discomfort and to promote toxin elimination via the bowel – broad scientific evidence for their benefit is lacking. On the contrary, concerns are increasing. The University Hospital Zurich notes in its statement on “myths and facts about the gut”:

“There is no scientific proof that people benefit from these measures. On the contrary – toxins already bound in the stool may actually be released again. Furthermore, such interventions are at least temporarily a massive disruption to the gut microbiome.”

So-called toxin binders such as zeolite are also of little use. As Prof. Dr. Martin Smollich explains in his book *The Nutrient Compass*:

“Zeolite and bentonite act as ‘super absorbers,’ binding nutrients from food so that they can no longer be absorbed in your gut.”

There are, however, good ways to support the gut and keep it active during fasting: for example, careful preparation days before starting a fast and, in addition, mineral waters rich in magnesium and calcium, which also provide the benefits of alkaline powder.

The effects of fasting are not diminished by avoiding intestinal interventions. In fact, our experience shows they are even more positive – as fasting participants who abstain from laxatives or enemas experience significantly fewer side effects and are more likely to achieve the real goal: fasting means well-being and vitality.

Trust your colon! 😉

Good to know for everyday life

Gut care means:

• structured mealtimes with proper breaks
• probiotic foods
• a wholesome, varied diet rich in fiber
• thorough chewing
• peace and mindfulness while eating

Gut care does NOT mean: cleansing with laxatives, toxin binders, enemas, flushes, or random probiotic supplements.

Myth 3 – Coffee and fasting don’t go together

False!

For a long time, coffee had a bad reputation. It was said to acidify the body, dehydrate it, and strain the cardiovascular system.

Today, research paints a very different – and highly positive – picture of coffee. It is a natural product, rich in phytonutrients, contains fiber, and can have many beneficial effects.

Studies show that regular coffee consumption may lower the risk of dementia, Parkinson’s disease, type 2 diabetes, heart attack, gout, and depression. Some research even describes a reduced risk for certain cancers (e.g., colon, breast, or prostate cancer). There is also growing evidence that coffee can contribute to increased life expectancy.

Coffee has even found its way into the current guidelines on non-alcoholic fatty liver disease by the German Society for Gastroenterology, as it may reduce the risk of developing this condition.

In addition to these benefits, coffee:

• has a mildly stimulating effect on metabolism – supporting weight loss, keeping the metabolism active during fasting, and helping regulate blood pressure
• stimulates autophagy during fasting, thereby supporting the body’s cellular recycling processes
• does not acidify the body – it is actually metabolized in an alkaline form
• contains polyphenols with anti-inflammatory properties
• does not dehydrate – instead, it contributes positively to fluid balance

As long as coffee is well tolerated and there are no issues such as heartburn, stomach, or intestinal problems, it can be a valuable companion to fasting and may even help reduce common fasting-related discomforts.

Ideally:

• prepare coffee freshly ground
• 1–2 cups per day are fine
• enjoy it black, without sugar or milk
• keep about one hour’s distance from fasting meals
• drink mindfully and in peace