Fasting and Its Benefits

Fasting and Its Benefits

Fasting is one of the easiest lifestyle measures to improve your health and well-being in the long term. There are many different ways of fasting. This article takes an in-depth look at these different types of fasting and their benefits. You will learn everything you need to know so that you, too, can easily integrate fasting into your everyday life.

Blog Author Jris Health Coach at CARE
Jris Bernet

Health Coach EN

Published in Nutrition
11 min read · Feb 27, 2024

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Table of content

What Is Fasting?

Fasting is a deliberate abstinence from food and sometimes liquids for a set period of time to promote physical and mental health, gain spiritual clarity, or achieve health benefits. The different fasting methods vary from complete abstinence to calorie-reduced diets.

Fasting is nothing new to our bodies. On the contrary, we are built for it. Our body has a sophisticated metabolic system, also known as the fasting or starvation metabolism, so that we can survive well even in times of need. Food was not always as readily available as it is today. Sometimes it was too cold, then too hot, or the saber-toothed tiger left nothing.

Our fasting metabolism, also known as hunger, ensured that humans did not starve and could go hunting with an empty stomach and a sharp mind.

Is Fasting Healthy?

Fasting stimulates many biochemical processes that have positive health effects. For example, insulin sensitivity can be increased, inflammation reduced, the immune system strengthened and blood pressure, bad cholesterol and weight lowered. The effects vary depending on the type of fasting and your personal state of health.

The following biomarkers have been shown to be positively influenced by fasting: [1]

  • HbA1c: HbA1c (hemoglobin A1c): This biomarker indicates the average blood glucose level over the last two to three months. Fasting, especially intermittent fasting, can help to lower HbA1c levels as it improves insulin sensitivity and can lead to a reduction in blood glucose levels.

  • Blood pressure: Studies show that fasting can lower systolic and diastolic blood pressure. This could be due to an improvement in vascular health, weight loss, and a reduction in insulin resistance.

  • hsCRP: hsCRP is a marker of inflammation in the body. Fasting can lower hsCRP levels, indicating a reduction in inflammatory responses in the body. This may be particularly the case with prolonged periods of fasting or intermittent fasting.

  • LDL cholesterol: The effects of fasting on LDL cholesterol (often referred to as "bad" cholesterol) can vary. Some studies report a reduction in LDL cholesterol with fasting, while others find no significant changes. The effects may depend on the type of fasting, duration, and diet composition during the eating periods.

  • Triglycerides: Fasting, especially intermittent fasting, can lead to a significant reduction in triglyceride levels. This is often associated with an improvement in lipid metabolic parameters and can reduce the risk of cardiovascular disease.

  • Visceral fat: Fasting can effectively help to reduce visceral fat. Visceral fat is the fat that accumulates around the internal organs and is associated with various health problems. By restricting calories and improving metabolic health during fasting, the amount of visceral fat can be reduced.

What Happens in the Body During Fasting?

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Depending on how active we are, our glycogen stores (also known as sugar or carbohydrate stores) are slowly but surely emptied. After 48 hours without food at the latest, our alternative energy system, the fasting metabolism, comes into play. Energy is now obtained from our own reserves, namely body fat.


For this purpose, fatty acids are released into the bloodstream and taken to the liver. The liver oxidizes them and forms ketone bodies. [1] Now we are in ketosis — have you heard of the ketogenic diet? You can also get into ketosis by cutting back on carbohydrates and eating more healthy fats and proteins.

The ketone bodies formed have the great advantage of crossing the blood-brain barrier and thus supplying the brain with energy. This emergency system enabled our ancestors to survive even in hard times with little or no access to food.


Autophagy is a cellular cleansing process in which cells break down and recycle damaged components to maintain cell health and improve cell function. It plays a crucial role in preventing disease, fighting infection and maintaining metabolism by helping balance cell renewal and the breakdown of cellular waste. Fasting is known to induce autophagy, as the lack of externally supplied nutrients causes the body to regenerate and cleanse itself internally, leading to improved health benefits. [1]

Your Lifestyle is Crucial

Now you might think that we no longer need this emergency system as plenty of carbohydrates are available. Carbohydrates provide readily available energy, so there is no problem, right?

That's somewhat true, but unfortunately, our body's adaptation to the new conditions will take quite a long time. And because we don't take this into account enough, we tend to eat not only too much but also too much of what makes us fat. That's what we're programmed to do!

As fat ensures our survival, it is advantageous for the body to have certain fat reserves and so we constantly strive to eat. Our ancestors not only had to look after their own food and spend many hours a day on the road, they also went to bed at dusk and left the cave at dawn. This means that they had plenty of exercise and regeneration time, sufficient daylight and darkness - without additional blue light from smartphones or tablets. They were also usually able to reduce stress relatively quickly as soon as the "natural" danger passed. They led a "species-appropriate" life in a circadian rhythm.

We have lost this lifestyle that was intended for us. Instead, we have a comfortable life with cars; supermarkets open 24 hours a day, artificial light, and many other conveniences, all of which ultimately contribute to so-called lifestyle diseases such as diabetes 2, Alzheimer's, cardiovascular disease, high blood pressure, and obesity.

Although we no longer have to fast out of necessity, we can still benefit from fasting metabolism. Fasting helps us to prevent typical lifestyle diseases, stay metabolically healthy and control our weight better. Regular fasting acts a bit like a reset button that can always bring us back into physical balance. [2]

Side Effects of Fasting

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Fasting can also lead to undesirable side effects [5], especially in the first three days when we switch from our usual carbohydrate to fat metabolism. During this time

  • headaches
  • Dizziness, circulatory problems
  • nausea
  • muscle cramps
  • mental upsets and even fits of rage. But this also shows the dependence on carbohydrates (sugar). You know the Snickers commercial with the diva in the locker room? “You're not you when you're hungry.” A wonderful example of what happens when you are on sugar withdrawal.

It should also be noted that certain types of fasting, such as OMAD — One Meal A Day, can lead to long-term nutrient deficiencies.

Who is Fasting Unsuitable For?

Even though fasting has many health benefits, a medical consultation is always recommended first. In particular, this applies to people with a pre-existing condition and those taking medications!

Fasting is not recommended for:

  • People having an eating disorder such as bulimia, anorexia, or binge eating
  • a low body fat percentage of less than 18.5% for women and less than 10% for men
  • Women who are not using hormonal contraception should not fast for longer than 12 to 14 hours
  • Pregnant people and during breastfeeding
  • Older people with low muscle mass and low body fat
  • Competitive athletes during a competition phase or during build-up training
  • Children and adolescents who are growing
  • Diabetics who inject insulin and/or take blood sugar-lowering medication

People with low blood pressure can generally fast but should be careful as dizziness and possibly even fainting can occur.

The 10 Major Benefits of Fasting

  1. Your metabolism improves — metabolic flexibility* is increased.
  2. Chronic inflammation can be reduced; pain relief occurs in inflammatory diseases such as rheumatism or arthritis.
  3. Autophagy is promoted, i.e., cell waste is removed more quickly, and defective cells are repaired. The immune system is strengthened.
  4. The liver, pancreas, and intestinal and gastric mucous membranes are relieved and can recover.
  5. Insulin sensitivity improves, severe blood sugar fluctuations are eliminated, and blood sugar stabilizes at a lower level.
  6. High blood pressure is also regulated at a lower level (if it is elevated).
  7. Neurogenesis (the formation of new brain cells) is stimulated.
  8. More ketone bodies are produced, your energy levels and ability to concentrate increase, and your brain fog disappears.
  9. Your hunger and satiety hormones ghrelin & leptin are restored; cravings are increasingly absent, the desire for sweet or salty foods decreases.
  10. And perhaps the most important point for many: regular fasting promotes healthy weight control. You can lose weight sustainably, which means you can maintain your desired weight!

*Metabolic flexibility is the body's ability to obtain energy from carbohydrates (glucose) and dietary fats (triglycerides) as well as from fatty acids (from your own body fat). Simply put, you are metabolically flexible if you can fast for a day without thinking much about food or feeling weak.

What Are Different Types of Fasting?

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(Almost) anyone can fast. You just need to find the right fasting method for you. In addition to classic types of fasting such as Buchinger therapeutic fasting, alkaline fasting, or intermittent fasting, there are new concepts such as intermittent fasting or dopamine fasting. This makes fasting easier or specifically avoids an individual habit that causes health problems.

Intermittent Fasting

Intermittent fasting, also known as intermittent fasting, has become very popular in recent years. This is thanks to the Japanese Yoshinori Oshumi, who was awarded the Nobel Prize in Medicine in 2016 for his discovery of autophagy. This demonstrated the health benefits of short-term fasting.

After just 14 to 18 hours without food intake, autophagy, our body's own recycling system, kicks in. Molecular cellular waste, which can promote diseases such as Parkinson's or type 2 diabetes in old age, is reduced in size, reassembled, and reused or disposed of. Bad bacteria and viruses are also eliminated during this clean-up process.

Intermittent fasting does not necessarily focus on healthy eating but more specifically on the length of fasting. Many people like intermittent fasting because it makes it easy for them to lose weight or maintain their desired weight. [3,6,7,8]


OMAD (One Meal A Day) is a form of intermittent fasting in which all calories for the day are consumed within a single, short window of time, typically within an hour. This practice can improve insulin sensitivity, contribute to weight loss, and have potential longevity benefits by effectively limiting daily calorie intake and putting the body into a state of fasting on a regular basis. [1] [4]

Water Fasting

Water fasting consists of completely abstaining from food intake and consuming only water for a period of 24 hours to several days. This fasting method can promote detoxification processes in the body, stimulate autophagy and help to improve cardiovascular health and reduce inflammation. [1]

Therapeutic Fasting According to Otto Buchinger

According to Otto Buchinger, therapeutic fasting involves avoiding solid food for a certain period of time and consuming only liquids, such as vegetable broth, herbal teas, water, and juice. Therapeutic fasting can be carried out for up to three weeks in clinics and is particularly appreciated by people suffering from chronic inflammatory diseases that cannot be improved with medication.

Longer therapeutic fasting periods of several weeks start slowly with build-up days and bowel evacuations and end in the same way with careful breaking of the fast. Detoxification and purification are buzzwords that almost always go hand in hand with fasting. In principle, we also detoxify in other ways via the liver, kidneys, skin, lungs, or lymphatic system. However, when we lose a lot of weight, toxins can be released from the fat cells and cause discomfort. For this reason, trying to lose a lot of weight in a short space of time should be avoided.

Fasting Mimicking Diet (FMD) According to Valter Longo

The latest trend is the Fasting Mimicking Diet, which goes back to the Italian-American gerontologist and biologist Prof. Dr. Valter Longo from the Institute of Longevity of the School of Gerontology at the Southern University of California in Los Angeles (UCLA).

He has studied the effects of fasting on chemotherapy there for many years. According to his studies, chemotherapy is more tolerable with intermittent fasting. Furthermore, autophagy can be achieved even without prolonged abstinence from food through a precisely prescribed composition of macros (proportion of carbohydrates, proteins, and fats).[3,4] Intermittent fasting is particularly suitable for people who find it difficult to abstain from food completely. [4]

Still, intermittent fasting is also a good option for young fertile women, who should generally not fast for more than 14 hours since traditional prolonged fasting can stress their hormone balance, preventing them from benefiting from the advantages of fasting.

Alkaline Fasting

Alkaline fasting is yet another completely different concept. Here, the focus of the diet is placed on alkaline foods. These should help to restore the acid-alkaline balance and deacidify the body. Alkaline fasting is particularly recommended for rheumatic complaints and digestive problems.

Fasting From a Religious Perspective

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There is hardly a religion that does not have a deeply rooted fasting period and methods. Religious fasting has the same health benefits, even if these are not the primary ones. Abstaining from food is intended to clear the mind and bring God closer to man. Jesus went into the desert to fast for 40 days, and Mohammed fasted when the Koran was revealed to him. To this day, many Buddhists do not eat after 12 noon in order to meditate better and thus achieve inner peace. They have been practicing intermittent fasting for a very long time.

Religious fasting periods also carry the social idea of sharing and friendship. For example, some collect money for the needy during the fasting period, and others give meals to neighbors and friends. During Ramadan, the ninth month in the Islamic lunar calendar, there is no eating or drinking from sunrise to sunset. In the evening, people get together with family and friends to share a meal. This is intended to promote community and solidarity.

Which Fasting Method Suits You?

Whether fasting according to Buchinger, Fasting Mimicking Diet according to Longo, alkaline fasting, intermittent fasting, or dopamine fasting — (almost) anyone can fast; the only question is which type of fasting suits you best. [5,6,7,8]

Finally, to answer whether fasting is healthy, we can say yes, definitely. But it should suit you and your lifestyle and take into account your health limits and requirements.

As a CARE member, we offer you regular fasting courses. From fasting for beginners to FMD (mock fasting) or 3-day OMAD followed by water fasting, you can try out fasting under CARE's guidance.

List of References

Blog Author Jris Health Coach at CARE

Jris Bernet

Health Coach EN at CARE Zurich

About the author

Jris is a health coach (nerd) and blog author at CARE. She has many years of experience as a coach for classic lifestyle conditions such as diabetes and women's health. She enjoys facilitating health challenges and courses. Fasting, keto, sleep, women's health and biohacking - Jris feels at home in these topics. When she's not working for CARE, she loves to listen to health podcasts and try out new (health) gadgets. Her credo: "It's never too late to start living a new lifestyle."