Intermittent fasting: small meal breaks with big effects

Scientific studies and a lot of media hype have turned intermittent fasting from a mere trend into a popular lifestyle. For good reason! After all, fasting has many health benefits, both physical and mental.

With this method, you eat your meals in a time-limited interval and then go without food for a certain period of time (a few hours to a few days). Water, tea and coffee without additives are allowed. When fasting, you can adjust the rhythm to your individual needs. This makes it a flexible method that can be easily integrated into everyday life.

The following sections explain the scientifically proven health effects that you can expect when fasting regularly.

An overview of the scientific studies on intermittent fasting

1. Intermittent fasting reduces inflammation in our bodies

There is a lot of evidence in research literature that suggests that intermittent fasting can reduce inflammation in our bodies. Inflammation is often the cause of chronic diseases such as Crohn’s disease, neurodermatitis or multiple sclerosis and is usually caused by excessive oxidative stress. This form of stress is produced when the body’s own antioxidants and free radicals get out of balance. In addition to inflammation, oxidative stress leads to a damage of tissue, blood proteins and DNA.

Intermittent fasting increases the body’s resistance to oxidative stress (1) and reduces certain inflammatory markers in our bodies (2, 3). This significantly reduces the risk of developing inflammation-related diseases.

2. Intermittent fasting regulates blood sugar levels and protects against diabetes

Intermittent fasting has a positive effect on insulin resistance, which makes it an interesting option for more and more health professionals to use as an (accompanying) therapy for patients with type 2 diabetes. That the method even has the potential to cure diabetes has been shown in studies with mice (4, 5), but these results are also supported by studies in humans (6, 7, 8). These have shown that regular fasting can reduce blood sugar levels by up to 6% and insulin levels by as much as 31%. Another study on diabetic rats found that fasting can help prevent kidney damage caused by diabetes (9).

Renowned nephrologists (specialists in kidney disease) such as the Canadian Dr. Jason Fung have also been using fasting for years to effectively treat diabetes patients.

Intermittent fasting is, however, also beneficial when diabetes does not yet exist, i.e. as a preventive measure (10). This is especially true for overweight people at risk for type 2 diabetes and for people with prediabetes.

Prediabetes is an early form of diabetes, which means that affected people already suffer from slightly elevated blood glucose levels, but the level typical for diabetes has not yet been reached. People with prediabetes usually already have to deal with insulin resistance. This means that the cells are no longer open up to the hormone insulin when trying to channel the transported sugar into the cell interior. Consequently, insulin and sugar accumulate in the blood and damage the blood vessels.

Intermittent fasting helps increase the insulin sensitivity of the cells again (11). This means that blood sugar can be broken down more quickly again. It also stimulates the formation of new insulin-producing cells in the pancreas.

Nevertheless, (pre) diabetic patients who want to benefit from intermittent fasting should discuss their fasting plans with their doctor in advance to make sure the method is suitable for them.

3. Intermittent fasting promotes cell health

Our cell health also benefits considerably from regular meal breaks. The renowned Japanese cell researcher Yoshinori Ohsumi was able to prove that during fasting periods a metabolic state is established in which a breakdown of non-functioning and a repair of damaged cells takes place – the so-called autophagy (in English: “self-digestion”) (12).

In simplified terms, this physical process involves the breakdown of cellular waste that would otherwise accumulate in the cells and hinder normal metabolic processes. In addition, the “self-absorption” of damaged cells produces energy that our bodies can use for other processes.

A 2019 study supports Ohsumi’s findings from the 1990s, for which he even received the Nobel Prize in Medicine in 2016 (13). The researchers succeeded in demonstrating that prolonged fasting leads to an increased formation of certain proteins that promote cell exchange. This makes it easier for the body to eliminate toxins in the blood.

When regular meal breaks promote physical recycling processes, this results in numerous positive health effects. Here is a list of the most important effects of increased autophagy on our body.

a) Intermittent fasting alleviates allergies and digestive intolerances

Autophagy can help reduce allergic symptoms and food intolerances. According to studies, even one fasting day per month has positive effects on allergic events in our bodies (14, 15, 16, 17).

Scientists currently assume that especially environmental or seasonal allergy problems can be improved with intermittent fasting. In addition, the available literature frequently points to improved lung function. Consequently, asthmatics in particular can benefit from the method.

There is also evidence in the research literature that intermittent fasting can help people with histamine intolerance (18, 19, 20, 21). By taking breaks from eating, the intestines and body system get a regenerative break, which helps to alleviate allergy symptoms.

b) Intermittent fasting improves skin texture and slows down ageing processes

Longer eating breaks also have a positive effect on the texture of our skin (22). Skin diseases such as acne can also be significantly reduced by intermittent fasting. The reason for this is that fasting has a positive effect on the release of growth hormones.

In addition, special anti-ageing enzymes, the so-called sirtuins, are at work during autophagy. They are also used as ingredients in anti-ageing creams. They ensure the longevity of the cells and help repair cell damage. Fasting can thus even contribute to faster healing of scars and strengthens the health of hair and nails.

Another reason for the improved skin condition: Intermittent fasting encourages people to drink more water and tea. This additionally promotes the vitality of our skin.

Apart from the positive effect on skin diseases and blemishes, scientific studies suggest that fasting can slow down ageing processes and increase life expectancy (23, 24). Various animal studies have shown that temporarily abstaining from food in combination with a calorie reduction increases the life rate by up to 38% (25, 26).

In another study, fasting rats even lived 83% longer than their non-fasting counterparts (27). In the experiment, the rats in the experimental group were given food every two days (then as much as they wanted), while the rats in the control group were allowed to eat all the time. This increased the lifespan of the animals, but also resulted in delayed growth. Incidentally, the effect on growth is also a reason why intermittent fasting is not suitable for children and teenagers.

Essentially, it is oxidative damage that is responsible for the ageing process in the human body. Intermittent fasting helps to make the cells more resistant to oxidative and metabolic stress. This can prevent, slow down or even completely repair potential damage (28, 29). Intermittent fasting helps prevent many infectious, muscular and neurodegenerative diseases that would reduce quality and expectancy of life under normal circumstances (30).

c) Intermittent fasting strengthens our immune system

As already mentioned, intermittent fasting ensures that our bodies produce fewer inflammatory neurotransmitters. This also strengthens our immune system and can even reduce autoimmune diseases, in which the misdirected immune system attacks the body’s own structures.

According to recent studies, fasting for three days leads to a complete regeneration of the immune system and an increased production of white blood cells (31). These are instrumental in fighting infections.

There is also a lot of evidence in the research literature that intermittent fasting under medical supervision can have a positive effect on the course of Hashimoto’s disease (32, 33). This is an autoimmune disease that is directed against the thyroid gland. Taking regular breaks from eating has been shown to relieve typical symptoms such as racing heart, sweating, increased blood pressure, diarrhoea, insomnia, increased anxiety, restlessness and cravings.

4. Intermittent fasting is good for your heart

Intermittent fasting can also significantly improve heart health.

The temporary avoidance of food helps prevent excessive accumulation of cholesterol, fat and other substances in the blood. Over time, plaque can harden and narrow the arteries and weaken the heart muscle. Fasting helps the body break down and use these substances, especially triglycerides (dietary fats) and negative LDL cholesterol (34).

By eliminating excess fat and cholesterol in the bloodstream and significantly lowering blood pressure (35), heart damage is actively counteracted (36, 37, 38) and the risk of heart attacks and other cardiovascular diseases is consistently reduced (39, 40, 41, 42).

This makes intermittent fasting an effective remedy for numerous symptoms of the so-called “metabolic syndrome” (43). This is a collective term for numerous health-threatening symptoms such as high blood pressure, excessive cholesterol and blood sugar levels as well as excess abdominal fat. Intermittent fasting not only relieves the symptoms of the syndrome, but has also been shown to improve the survival rate of affected patients (44, 45).

5. Intermittent fasting has a positive effect on your thyroid and hormonal health

There is a lot of evidence in scientific literature indicating that conventional diets have a negative effect on metabolism and hormonal balance. Intermittent fasting, on the other hand, has been shown to improve metabolic efficiency and to have a positive effect on hormonal balance (46).

In a 2009 study, researchers found that regular eating breaks stimulate thyroid function by promoting the conversion of inactive T4 hormones into active T3 hormones (47). The thyroid hormone T3 is crucial for energy burning in our bodies and ensures a healthy metabolism.

Intermittent fasting can also be used as a supportive therapy measure for PCOS patients (48). Polycystic ovary syndrome, or PCO syndrome for short, is a hormone disorder that often occurs in women of childbearing age. The syndrome is often accompanied by obesity, acne, low mood and disturbed sugar metabolism ( including type 2 diabetes) – in other words, many symptoms that intermittent fasting has been shown to alleviate. Consequently, it is not surprising that fasting is used as a treatment for endocrinological complaints of this kind (49).

6. Intermittent fasting reduces your appetite and is a fat killer

People who fast regularly strengthen their natural perception of hunger. The assumption that after skipping a meal there is an increased appetite that leads to overeating has been scientifically disproved. On the contrary, studies have even shown that fasting people feel fuller more quickly than people who do not fast regularly (50, 51). A study published in the journal “Obesity” in July 2019 also supports these findings and concludes that fasting has an appetite-suppressing effect in long-term fasters (52).

Apart from this, it has been shown that short-term and regular fasting makes our metabolism more efficient. Meal breaks can increase the metabolic rate by up to 14% (53). The reason for this is an increased release of epinephrine, a hormone involved in fat loss.

Intermittent fasting also effectively promotes fat loss. After 8 to 12 hours of not eating, the body switches from glucose to fat burning (“metabolic switch”). If no food is consumed over a longer period of time, the body runs out of glucose as an energy source at some point, which is why the body’s own fat reserves are used (54, 55).

Particularly advantageous: During ketosis, i.e. fat metabolism, in particular visceral abdominal fat, which is considered harmful, is broken down (56). A study conducted in 2020 showed that overweight study participants who adhered to an intermittent fasting protocol were able to significantly reduce their abdominal fat and waist circumference compared to the control group (57).

Further scientific evidence for more efficient fat loss during fasting can be found in a study from 2016 (58). In the experiment, the study participants lost an average of 1.3% of their body weight over a period of two weeks with the help of fasting. Over a period of eight weeks, they even lost up to 8%. For a person weighing 200 pounds, this would mean that he or she could lose up to 16 pounds in two months.

It is also worth pointing out that fasting performs at least as well as classic calorie-reduced diets in comparative studies on weight reduction, and in some studies even better (59, 60).

Particularly noteworthy: Intermittent fasting leads to a reduction in fat deposits even when the amount of food and the weight of the test persons is similar to that of a control group with unrestricted eating times (61).

In a pilot study, fasting protocols have been shown to be effective in preventing weight gain during periods of high eating, such as the time before Christmas (62).

One of the biggest advantages of fasting is that it affects the calorie balance in two ways: On the one hand, the breaks in eating make it easier to reduce the calorie intake, and at the same time, more calories are burned due to the increased performance of the metabolism. Fasting is therefore considered one of the most effective and sustainable solutions for weight loss and weight maintenance.

Another plus: regular fasting strengthens the health of the liver and pancreas (63). A high-sugar diet or excessive alcohol consumption can lead to fat deposits on the liver. These increase the risk of diabetes, arteriosclerosis and cardiovascular diseases. By switching to fat metabolism during intermittent fasting, the dangerous liver fat is rapidly broken down.

At the same time, the liver is relieved by the regular breaks in eating, as fewer toxic intermediate products are deposited in it during the fasting periods. Fasting for hours or days also causes the liver to produce a protein that slows down the absorption of fatty acids in the liver (64). This effectively counteracts fat formation in the liver.

7. Intermittent fasting is an effective means of fighting and preventing cancer

Fasting has further advantages: It is an effective means of cancer prevention and helps our bodies to fight cancer cells.

The German physicist and Nobel Prize winner Otto Warburg succeeded in proving that cancer cells prefer to use glucose for energy production and growth. By switching from glucose to fat metabolism during fasting, cancer cells are deprived of their “food”. Consequently, intermittent fasting can help to weaken or even destroy cancer cells (65).

In the field of cancer research, there is also evidence that intermittent fasting significantly reduces the likelihood of spontaneous tumours occurring. This can be explained on the one hand by the fact that it makes healthy cells more resistant to stress. At the same time, there is scientific evidence to suggest that regular fasting makes the cancer cells of some types of cancer more receptive to chemotherapeutic medications, which increases the effectiveness of the treatment. In many cases, fasting has even been shown to help mitigate the side effects of chemotherapy (66, 67, 68).

However, cancer patients who want to benefit from intermittent fasting as part of their treatment should not do so without medical supervision, despite the promising research results.

8. Intermittent fasting has a positive effect on the gastric and intestinal tracts

The gastrointestinal tract also benefits from intermittent fasting. The breaks in eating considerably relieve the intestines, the mucous membrane can regenerate and form anew and the microbiome can find its way back to its original, optimal composition. Thus, temporarily abstaining from food offers the intestines a favourable opportunity to regenerate.

Additionally, scientific studies have shown that fasting leads to an improvement in the composition of the intestinal flora (69). Research also suggests that bacterial diversity and the number of bacteria that have a beneficial effect on gut health (e.g. bifidobacteria) increase significantly as a result of temporary food deprivation.

9. Intermittent fasting improves our sleep

Thanks to the relief of the entire organism, intermittent fasting also influences the human sleep cycle. For example, a study in the field of sleep research suggests that 18-6 (a type of intermittent fasting that involves eating in a 6-hour time window) alters the genetic network of the circadian rhythm (the internal clock), thereby improving sleep quality (70).

In another study on mice, researchers came to a similar conclusion (71). They divided the mice into two groups, with one group having food available around the clock and the other being fed according to the principle of intermittent fasting. The amount of calorie and fat intake was the same in both groups. The result: The mice that had constant access to food gained weight. It was also observed that the mice that fasted were more alert and productive during the day and slept more deeply during sleep periods. The researchers suspect that the ketones formed during fasting are responsible for influencing circadian genes.

10. Intermittent fasting preserves muscle mass

A study by the University of Illinois found that intermittent fasting – unlike many diets – helps maintain muscle mass while reducing body fat (72). The study compared the weight trajectories of two groups of overweight participants. One group followed a conventional, low-calorie diet, the other followed a fasting plan. After twelve weeks, both groups had lost fat mass, but the fasting group retained significantly more muscle mass.

Researchers explain this result by the fact that our bodies produce more (up to five times as much) growth hormone (HGH) during fasting periods. The hormone HGH is largely responsible for building and maintaining muscle and supports fat burning (73, 74, 75).

11. Intermittent fasting boosts our cognitive performance and mental health

However, intermittent fasting does not only promote physical health. Recent studies have also shown that it can boost mental clarity, improve cognitive function and reduce oxidative stress in our brains (76). As a result, people who fast often report a decrease in depression and anxiety, an improved relationship with food, and a more positive mood (77). One reason for these positive effects on mental health is the increase in brain-derived-neurotrophic factor (BDNF), a hormone that can lead to depression and low mood when deficient (78, 79, 80, 81). In addition, the effects are due to the fact that fasting increases the production of the “happiness hormone” serotonin.

Research also suggests that intermittent fasting has a positive effect on long-term brain health. Numerous studies show that fasting supports the growth of neurons in the human brain, improving memory and cognitive performance (82, 83, 84, 85). A 2015 study conducted on both humans and animals also shows that intermittent fasting can support recovery after brain injury or stroke (86). Regular meal breaks also strengthen the function of the mitochondria (the “power plants of our cells”) (87).

Other studies show that fasting is incredibly valuable as a preventative measure for potential diseases. For example, it reduces the risk of developing neurological diseases such as Alzheimer’s and Parkinson’s (88). In addition, intermittent fasting has been shown to protect the brain from age-related decline (89, 90, 91, 92).

The current state of research and its boundaries

The potential of intermittent fasting as a method for healthier living and ageing is huge. And fortunately, researchers worldwide are now focusing on the scientific investigation of this method. The findings from a large number of published studies are promising and suggest that fasting is an effective remedy for a number of diseases and positively influences physical and mental health in many ways.

It is worth noting that some of the findings to date have come from animal or short-term human studies. This is mainly because intermittent fasting is a very young research field. This circumstance does not make the results worthless, but more in-depth research and long-term studies are necessary to be able to make general statements.

Last but not least, every body acts differently, which means you will notice pretty quickly whether intermittent fasting is good for you or not. In the next section you will find out for which groups of people intermittent fasting is not suitable or only suitable after consulting a doctor.

Who should not do intermittent fasting?

Intermittent fasting is a natural, gentle and sustainable method that most people can benefit from in the long term.

However, people with pre-existing conditions should be cautious and talk to their doctor before starting. This is especially true for people with low blood pressure, migraines and chronic diseases such as diabetes and cancer. Every case is different and only the attending doctor can assess whether and to what extent intermittent fasting can be an individual option. That is why professional support and regular check-ups are important; sometimes, for example, medication has to be adjusted during the course of the programme.

Intermittent fasting is not suitable for pregnant women or breastfeeding mothers and people who suffer from eating disorders, underweight or amenorrhoea (lack of menstruation).

Intermittent fasting: Your health booster on all levels

Even though further research is needed to expand and validate the results of previous studies, so far there are many indications of the far-reaching potential of intermittent fasting.

Current research suggests that intermittent fasting is truly multi-talented in terms of health promotion. It can comprehensively strengthen physical and mental health and protects against a wide range of diseases (for an overview, see the chart).

And the best thing is: to benefit from the method on all levels, you don’t need a complicated diet plan, give up your favourite food or even count calories.

All it takes is ONE conscious change – namely WHEN you eat and when you don’t eat.

We believe intermittent fasting can also be your partner for a healthy and happy life.

It…

• is simple and can be easily integrated into everyday life.

• really works – in a natural and sustainable way.

• is beneficial for your body and mind.

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