Fasting is not merely a spiritual practice but a profound biological transformation process for the human body and brain. Modern scientific research has revealed that fasting accelerates the process of generating new neural cells (neurons) in the human brain, which in scientific terms is called neurogenesis. This process is actually made possible through a special type of metabolic switching, where the body begins to rely on ketones instead of glucose for energy acquisition. This metabolic switching not only protects brain cells but also provides the necessary environment for building new cells. In this paper, we will try to understand this deep relationship between fasting and neurogenesis and explore how fasting can prove to be a natural treatment for our brain.

The process of neurogenesis occurs in specific parts of the human brain, particularly in the hippocampus, which is the center of memory and learning. During fasting, when glucose levels decrease in the body, the body searches for alternative energy sources. In this situation, stored fats in the liver are broken down to form ketone bodies, which are not only the best source of energy for the brain but also stimulate the process of neurogenesis. These ketone bodies activate stem cells present in the brain, which transform into new neurons. During this process, the production of a special protein BDNF (Brain-Derived Neurotrophic Factor) increases, which plays an important role in the birth of new neurons and strengthening their connections. BDNF actually works like a fertilizer for the brain, promoting not only the birth of new neurons but also protecting existing neurons. The increase in BDNF levels during fasting occurs in several ways. First, fasting increases norepinephrine levels in the body, which directly triggers BDNF production. Second, fasting reduces oxidative stress, which inhibits BDNF production. Third, fasting reduces inflammation, which can negatively affect BDNF production. The combined result of these three factors is that fasting significantly increases BDNF levels, which accelerates the neurogenesis process. Additionally, fasting also accelerates the process of autophagy, through which damaged or unnecessary brain cells are cleaned, making space for new neurons. This process of autophagy is not only beneficial for brain health but also helps prevent neurodegenerative diseases like Alzheimer’s and Parkinson’s. The process of neurogenesis during fasting occurs in different stages. In the first stage, neural stem cells divide and new cells are formed. In the second stage, these new cells migrate and reach their correct location. In the third stage, these cells differentiate into complete neurons. In the fourth stage, these new neurons connect with existing neural networks. Fasting positively affects all four stages, resulting in accelerated neurogenesis process. Research has shown that regular fasting can increase the rate of new neuron production in the hippocampus by up to 50%, which leads to significant improvement in memory and learning abilities.

Metabolic switching is actually a survival mechanism that becomes active during fasting. When we eat food, our body uses glucose as primary energy. But when we fast and don’t eat food, glucose levels decrease in the body. In response, the body searches for alternative energy sources. This is when metabolic switching occurs. The body begins to break down fat cells, resulting in the production of ketone bodies in the liver. These ketone bodies are not only a more efficient source of energy for the brain but also reduce oxidative stress and control inflammation, which provides an ideal environment for neurogenesis. The process of metabolic switching occurs in different stages. In the first stage, when we eat food, our body uses glucose as primary fuel. In the second stage, when we don’t eat anything for 8-12 hours, stored glycogen in the body begins to deplete. In the third stage, when glycogen is depleted, the body begins to break down fat cells, producing fatty acids and glycerol. In the fourth stage, the liver converts fatty acids into ketone bodies, which consist of beta-hydroxybutyrate, acetoacetate, and acetone. These ketone bodies cross the blood-brain barrier and reach the brain, where they produce energy through mitochondria. Ketone bodies produce energy more efficiently than glucose, resulting in less oxidative stress. Additionally, ketone bodies trigger various signaling pathways that promote neurogenesis. For example, beta-hydroxybutyrate inhibits histone deacetylases, resulting in increased expression of BDNF and other neurotrophic factor genes. Not only that, ketone bodies also strengthen the antioxidant defense system, which protects brain cells from oxidative stress. During metabolic switching, the number and function of mitochondria also increase, which is called mitochondrial biogenesis. This process provides more energy to brain cells and extends their lifespan. Research has shown that metabolic switching not only promotes neurogenesis but also improves synaptic plasticity, which strengthens brain connections. All these factors together lead to improved brain health and reduce the risk of neurodegenerative diseases.

There are numerous cognitive benefits of neurogenesis that occurs during fasting. The birth of new neurons improves memory, increases learning ability, and slows down the process of cognitive decline. Research shows that people who fast have reduced risk of neurodegenerative diseases like Alzheimer’s and Parkinson’s. Additionally, fasting also improves brain plasticity, enabling the brain to process new information more effectively. All these benefits are actually the result of the mutual relationship between metabolic switching and neurogenesis. The cognitive benefits of fasting manifest in several ways. First, fasting improves cognitive flexibility, meaning we can adapt our thinking according to different situations. Second, fasting improves problem-solving skills, because new neurons help us find new solutions. Third, fasting increases focus and concentration, because ketone bodies provide a more stable energy source for the brain. Fourth, fasting reduces neuroinflammation, which plays an important role in problems like depression and anxiety. Fifth, fasting slows down the brain aging process, as a result of which cognitive abilities remain intact for a longer period. To achieve these benefits, it is essential that fasting is regular. Research shows that fasting two to three times a week may be sufficient to obtain cognitive benefits. However, the duration and frequency of fasting may vary according to each person’s health and age. When fasting, it is also important to ensure that when breaking the fast, a balanced and nutritious diet is eaten, so that the body receives all the nutrients necessary for neurogenesis. Especially, the use of omega-3 fatty acids, antioxidants, and B vitamins further strengthens the neurogenesis process.

Different methods of fasting can have varying effects on neurogenesis. Intermittent fasting, which involves limiting eating times, has proven particularly effective in triggering neurogenesis. Similarly, prolonged fasting, where fasting is done for 24 hours or more, can further accelerate the neurogenesis process. Each type of fasting has its own mechanism, but the goal is the same: to improve brain health through metabolic switching. There are several types of intermittent fasting, including the 16/8 method (16 hours of fasting and 8 hours of eating time), the 5:2 method (eating normally for 5 days a week and limiting calorie intake for 2 days), and alternate day fasting (fasting one day, eating normally the next day). Each method has its own benefits, but research shows that the 16/8 method has proven most effective for neurogenesis. In prolonged fasting, when fasting exceeds 24 hours, the autophagy process accelerates even further, resulting in cleaning of damaged brain cells and creating space for new neurons. However, prolonged fasting may not be suitable for everyone, especially for those who are fasting for the first time or have specific health issues. Therefore, it is essential to consult a doctor before starting fasting. Time-restricted eating is also an effective method, in which eating time is limited to specific times of the day. Research shows that eating food in the early hours of the day (early time-restricted feeding) proves more beneficial for neurogenesis, because it aligns with the body’s natural circadian rhythm. Periodic fasting, in which several consecutive days of fasting are observed each month, has also proven effective in triggering neurogenesis. This method can be particularly useful for those who cannot fast daily. When choosing the type of fasting, it should be considered that the method should be according to your lifestyle, health, and personal preferences. It is better to start with mild methods initially, then gradually increase the duration and frequency of fasting.

Fasting not only creates new brain cells but also protects existing cells. During fasting, the process of autophagy accelerates, in which damaged or unnecessary cells of the body are cleaned. This process cleans brain cells from accumulating toxic substances that can cause neurodegenerative diseases. Thus, fasting provides a dual benefit: construction of new cells and repair of old cells. The process of autophagy is actually a natural cleaning system that breaks down damaged proteins and organelles present in cells. Fasting increases the expression of genes that activate autophagy, while decreasing the expression of genes that inhibit it. As a result, toxic protein aggregates present in brain cells, which are seen in Alzheimer’s disease, are cleaned. Fasting also improves mitochondrial function, resulting in more efficient energy production and reduced oxidative stress. Both these factors are extremely important for the protection of brain cells. Additionally, fasting reduces neuroinflammation, which is a major cause of many neurodegenerative diseases. Fasting decreases the production of inflammatory cytokines, while increasing the production of anti-inflammatory molecules. This balance provides a healthy environment for brain cells. Fasting also reduces oxidative stress, which is a major cause of damage at the cellular level. During fasting, the antioxidant defense system strengthens, resulting in reduced effect of free radicals. All these factors together protect brain cells and slow down neurodegenerative processes. Research has shown that people who fast regularly have significantly reduced risk of dementia and other neurodegenerative disorders.

The duration of fasting deeply affects the neurogenesis process. Research shows that metabolic switching begins after 12 to 16 hours of fasting, but longer fasting can prove more beneficial for neurogenesis. However, the ideal duration of fasting may vary according to each person’s body. It is also important that the fasting process is regular, because intermittent fasting keeps neurogenesis constantly activated. In short-term fasting (12-16 hours), metabolic switching primarily begins and BDNF levels increase slightly. In medium-term fasting (16-24 hours), the autophagy process accelerates and the neurogenesis process increases significantly. In long-term fasting (more than 24 hours), stem cell activity increases and the rate of neurogenesis can increase dramatically. However, long-term fasting requires caution, because it may not be suitable for everyone. Age also affects the ideal duration of fasting. Medium-term fasting may prove more beneficial for young people, while short-term fasting may be safer for elderly people. Health condition is also important – for those who are fasting for the first time, short-term fasting is better initially. The frequency of fasting is also important. Research shows that fasting 2-3 times a week can give the best results for neurogenesis. There should be adequate intervals between fasts, so that the body gets a chance to recover. Continuous fasting may not be beneficial, because it can cause deficiency of nutrients in the body, which are necessary for neurogenesis. When determining the duration and frequency of fasting, it should be considered that the purpose of fasting is to improve health, not to cause harm.

Foods eaten during fasting and when breaking fast can affect the neurogenesis process. Foods rich in antioxidants, such as berries, green leafy vegetables, and nuts, further strengthen the neurogenesis process. Similarly, foods rich in omega-3 fatty acids, such as fish and walnuts, play an important role in building new neurons. When breaking fast, it is essential to eat a balanced diet that can provide all necessary nutrients. Protein is essential for building neurons, so when breaking fast, protein-rich foods such as eggs, lentils, and lean protein sources should be used. Carbohydrates provide energy, but complex carbohydrates such as whole grains, vegetables, and fruits should be preferred. Healthy fats, especially omega-3 fatty acids, are extremely important for brain health. Vitamins and minerals are also essential for neurogenesis. Vitamin B12, folate, vitamin D, and zinc are particularly important. Deficiency of these nutrients can stop the neurogenesis process. During fasting, maintaining hydration is also very important. Dehydration can affect brain functions and slow down the neurogenesis process. During fasting, water, herbal tea, and other non-caloric beverages should be continued. When breaking fast, overeating or eating processed foods should be avoided, because they can reduce the benefits of fasting. Instead, one should eat slowly and in a balanced manner.

Fasting not only changes metabolic processes but also affects gene expression. Research shows that fasting activates genes related to neurogenesis, brain protection, and longevity. These genetic changes can play an important role in maintaining long-term brain health. Fasting increases the activity of proteins called sirtuins, which are related to cellular health and longevity. SIRT1 and SIRT3 are particularly important, which improve mitochondrial function and reduce oxidative stress. Fasting also activates FOXO transcription factors, which control the expression of genes related to stress resistance and longevity. Fasting also activates the Nrf2 pathway, which strengthens the antioxidant defense system. All these genetic changes together protect brain cells and promote neurogenesis. Fasting also causes epigenetic modifications, which can affect gene expression for a long time. For example, fasting causes changes in DNA methylation patterns, which can slow down the aging process. These epigenetic changes can be transferred not only in the fasting individual but also to their offspring, which is called transgenerational inheritance. Research has shown that fasting also maintains telomere length, which is an important marker of the aging process. All these genetic and epigenetic effects together demonstrate the long-term benefits of fasting.

Fasting improves blood circulation, which provides more oxygen and nutrients to the brain. This improved blood circulation provides a favorable environment for neurogenesis, because adequate supply of oxygen and nutrients is essential for the birth and growth of new neurons. Fasting can also accelerate the process of angiogenesis (formation of new blood vessels), which improves blood supply to the brain. Additionally, fasting reduces blood viscosity, resulting in easier blood flow. Fasting also improves endothelial function, which is important for blood vessel health. All these factors together improve cerebral blood circulation. As a result of improved blood circulation, brain cells receive more oxygen and glucose, which is essential for their function. Additionally, as a result of improved blood circulation, the removal of metabolic waste products also improves, which is important for brain health. This improvement in cerebral blood flow caused by fasting is particularly evident in the hippocampus, which is the center of neurogenesis. Research has shown that people who fast regularly have shown significant improvement in cerebral blood flow, which is related to improved cognitive functions.

Fasting reduces oxidative stress, which can be harmful to brain cells. The reduction in oxidative stress not only protects existing brain cells but also provides a favorable environment for the birth of new cells. Oxidative stress occurs when free radical production exceeds the antioxidant defense system. Fasting strengthens the antioxidant defense system, resulting in reduced effect of free radicals. Fasting increases the production of antioxidants such as glutathione. Additionally, fasting also improves mitochondrial efficiency, resulting in fewer free radicals being produced. Fasting activates the Nrf2 pathway, which regulates this antioxidant defense system. As a result of reduction in oxidative stress, the lifespan of brain cells increases and the neurogenesis process accelerates. Research has shown that fasting animals have found lower markers of oxidative damage in their brains. This effect was particularly evident in the hippocampus. Reduction in oxidative stress is not only beneficial for neurogenesis but also improves synaptic plasticity, which improves memory and learning ability.

Research in the field of fasting and neurogenesis is still in its early stages. In the future, we will better understand how different methods of fasting affect neurogenesis, and which methods can prove most beneficial for which individuals. In upcoming research, scientists will be able to study how different fasting protocols can be personalized. It will also be seen how fasting can be combined with other interventions to maximize its effects. For example, combining fasting with exercise can achieve synergistic effects on neurogenesis. Future research will also examine how the effects of fasting vary in different age groups. The long-term effects of fasting will also be studied. Clinical trials will examine whether fasting can be useful in treating neurodegenerative diseases. Research will also be done on how long fasting should be continued to maintain its effects. At the molecular level, it will be studied how fasting signals reach the brain. It will also be seen whether the effects of fasting can be mimicked by pharmacological agents.

Fasting should be adopted as a healthy habit rather than merely a religious worship. You can start with intermittent fasting and then gradually move towards prolonged fasting. It should be remembered that maintaining hydration is very important while fasting. Before starting fasting, it is essential to consult your doctor, especially if you have any medical problems. Start with easy targets, such as fasting for 12 hours once a week. Then gradually increase the duration and frequency of fasting. During fasting, pay attention to your body’s signals. If you feel dizzy, excessively weak, or have other problems, break the fast. When breaking fast, eat light and balanced food. Avoid overeating or eating unhealthy foods. During fasting, light exercise can be beneficial, but avoid intense exercise. To make fasting part of your daily life, adopt it like a routine. To maximize the benefits of fasting, combine it with other healthy habits, such as balanced diet, regular exercise, and good sleep.

There are also psychological benefits of neurogenesis resulting from fasting. This process can prove useful in mental health issues like depression and anxiety. The birth of new neurons helps improve mood. Fasting improves serotonin levels, which plays an important role in mood regulation. Fasting also releases endorphins, which are related to feelings of happiness. Fasting also improves GABA function, which can help reduce anxiety. Fasting reduces neuroinflammation, which is a major cause of depression. Fasting also improves the stress response system, as a result of which cortisol levels normalize. Fasting improves cognitive function, which can increase self-esteem. Fasting also strengthens willpower, which is important for mental health. All these factors together lead to improved mental health.

Neurogenesis caused by fasting improves brain flexibility (neuroplasticity), enabling us to learn new skills and adapt to new situations. Neuroplasticity is the brain’s ability to adapt according to experiences. Fasting improves synaptic plasticity, as a result of which connections between neurons strengthen. Fasting increases the density of dendritic spines, which are important for synaptic connections. Fasting improves long-term potentiation (LTP), which is the cellular basis of learning and memory. Fasting increases the production of neurotrophic factors, which are essential for neuroplasticity. All these factors together improve brain flexibility, as a result of which we can learn new skills more easily, solve problems better, and adapt ourselves to new situations.

Fasting actually works as natural medicine for brain health. It not only creates new brain cells but also proves helpful in improving brain functions. Properly observed fasting can increase our cognitive abilities and provide us with long-term brain health. To obtain the benefits of fasting, it should be adopted regularly and properly. Fasting should be made part of life by combining it with other healthy habits. Among different types of fasting, the method that suits your health and lifestyle should be chosen. Before starting fasting, it is essential to consult a doctor, especially if you have any medical problems. During fasting, attention should be paid to body signals and fasting should be broken when necessary. When breaking fast, balanced and nutritious food should be eaten. Fasting should be viewed not merely as a method of weight loss but as a tool for overall health. Regular fasting not only improves brain health but also proves beneficial for the entire body.