In a world saturated with fads and instant health solutions, fasting stands out as a beacon of simplicity and ancient wisdom. But, faced with the chaos of information and misinformation, some fundamental questions arise: Why has fasting been hailed as something so incredible? What are the mechanisms behind this practice?
Does more time without eating always translate into more health benefits, or are there limits that we should respect? What can happen to thin people who undertake prolonged fasting? What is the history of fasting?
Did our ancestors already know the secrets that we are just beginning to uncover? For millennia, fasting has been a master key in the quest for vitality, mental clarity and healing, practiced by great minds and civilizations throughout history. Without the technology or scientific knowledge we have today, these cultures already understood a hidden power behind this simple practice, something that modern science is only now beginning to uncover in more depth.
History shows us that fasting was not just a consequence of food scarcity, but often a deliberate choice, charged with wisdom and purpose. Imagine, for a moment, Angus Barbieri, who in 1965, under medical supervision, fasted for an impressive 382 days, losing around 125 kg without any solid food. This extraordinary case shows us not only the transformative potential of the human body, but also our incredible survival and adaptation mechanisms.
Going back even further, to around 460 to 370 BC, we find figures such as Hippocrates, the father of Medicine, who already documented the benefits of fasting, including the reduction of seizures in patients with epilepsy. Socrates, the brilliant mind of Ancient Greece, also fasted, seeking clarity and mental resistance before his philosophical struggles. From the magnificent civilizations of ancient Egypt, through Greece and Rome, to the heart of spiritual traditions around the world, fasting has been revered as a transcendental practice.
In the incredible diversity of nature, fasting also proves to be a sophisticated strategy for survival or recovery. Consider the lion, for example, which after an exhausting hunt, enters an intensive period of fasting and rest. Diverse species, from the smallest migratory birds to large marine mammals, adopt periods of fasting as a way of adjusting their bodies to cycles of abundance and scarcity, or as a means of purifying and rebalancing their internal systems before significant stages in their lives.
, such as long migrations or changes of season. Snakes also fast, especially before shedding their skin, a process known as ecdysis. This process requires a significant amount of energy and biological resources.
During fasting, by reducing the energy demand of digestion, snakes focus their energy on skin regeneration, facilitating more efficient and healthier molting. Likewise, many reptiles and birds enter a fasting state while incubating their eggs. In this context, fasting can optimize energy allocation for metabolic processes important for maintaining the ideal temperature for embryo development.
While animals instinctively turn to fasting to adapt and recover, people throughout history have adopted this practice, drawing on direct experience and knowledge passed down from generation to generation. For a long time, the details of the biological mechanisms behind fasting remained a mystery, until, in the early 20th century, we experienced a significant advance in understanding how the human body responds to fasting. In 1921, Dr Russell M.
Wilder of the Mayo Clinic marked a turning point by exploring the potential of fasting to reduce or even eliminate seizures in patients with epilepsy. Until then, the medical community recognized the benefits of fasting, but the underlying mechanisms were a mystery. Wilder identified ketosis, a metabolic state induced by fasting where the body breaks down fats for energy in the absence of glucose.
He realized that this change Metabolic stabilizes neural activity and can reduce the excitability that leads to seizures. Inspired by this discovery, he applied the principle of ketosis to develop the ketogenic diet, a high-fat, moderate-protein, low-carb diet that was designed to induce ketosis without the need for complete fasting. This advance offered a new therapeutic approach for patients with epilepsy, mimicking the metabolic benefits of fasting.
Although the ketogenic diet is an example to explain the concept, it is important to remember that the focus of this video is fasting and its direct effects on health. Another notable effect of fasting is the activation of autophagy, a cellular cleansing mechanism that our bodies naturally employ. Autophagy, which literally means "eating oneself" in Greek, is the process by which cells degrade and recycle their damaged or unneeded components.
This internal cleaning process is crucial for maintaining cellular health, helping to eliminate defective proteins and worn-out organelles. Controlled periods of food restriction are one of the most efficient ways to activate autophagy. In the absence of constant food intake, our body seeks to optimize its internal resources, beginning this vital process of cleansing and renewal.
While activating autophagy has been linked to reducing the risk of several diseases, including cancer and neurodegenerative conditions such as Alzheimer's, it is essential to understand that it is just one of many processes that contribute to the body's complex defense against these and other pathologies. Stimulating autophagy through well-managed fasting can offer significant benefits, but we also need to recognize that activating autophagy goes beyond fasting to encompass a variety of practices that can stimulate or aid this vital process of cellular cleansing. Let's look at some examples: High-intensity exercise: The high energy demand of these activities signals to the body the need to optimize its resources, recycling damaged cellular components to sustain the effort.
Cold shower: Exposure to cold activates heat stress that can induce cellular survival mechanisms, including autophagy. Autophagy gained global attention in 2016, when Japanese scientist Yoshinori Ohsumi was awarded the Nobel Prize in Medicine for his pioneering research. Ohsumi elucidated the molecular mechanisms of autophagy, demonstrating how cells recycle damaged components to preserve cellular health and promote longevity.
Their work has not only shed light on this vital process, but also opened new avenues of research into how dysfunctions in autophagy are linked to various diseases, suggesting new avenues for innovative therapies. An interesting example of the practical application of this knowledge is the long-term study conducted at the National Primate Research Center in Wisconsin, United States, which began in 1989. This study investigated the effects of caloric restriction, a potential stimulator of autophagy, on health and longevity of monkeys and brought impressive results.
Among the participants, two monkeys, Owen and Kanto, stood out. Two decades after the start of the study, in 2009, as we can see in this image, the difference was notable. Kanto, on the left, was under restriction, consuming 30% fewer calories but getting all the nutrients he needed; was healthier and had a lower incidence of age-related illnesses compared to Owen, who followed a standard diet with no restrictions.
This large monkey study is just one piece of the puzzle in the relationship between eating habits and health. Science shows us that well-managed periods of fasting not only stimulate autophagy, essential for maintaining cellular health, but also positively influence several biomarkers. This includes reducing inflammation, improving insulin sensitivity, and optimizing energy metabolism.
All of these factors are incredibly important in maintaining health and body composition. Well-controlled fasting reveals another fascinating aspect of its impact on health: strengthening the immune system. As we have already seen, well-managed fasting is like a switch that activates an internal cleaning process called autophagy.
This cellular "detox" is controlled by special signals within our body, called mTOR and AMPK. When we fast, we pause the "Time to Grow and Multiply" (mTOR) signal and turn on the "Time to Clean" (AMPK) signal, as if telling our cells, "Let's tidy up the house instead of bringing in more things inside. ” And the brain?
Ah, it loves this cleaning. Fasting helps create new neurons, yes, new brain cells, and strengthens the connections between them. This means sharper memory and a more agile brain.
To benefit our brain health, fasting offers a well-deserved rest to our digestive system, an advantage that we cannot ignore. During fasting, by taking a break from eating, we allow the digestive system to recover from mild inflammation and adjust its functioning. , improving nutrient absorption and waste elimination.
We talk a lot about the wonders of autophagy and the many benefits of fasting. Autophagy is indeed an incredible and fundamental biological mechanism. However, just like an overflowing river, it can flood.
In a city, excessive autophagy can have unwanted effects. This process, when not properly controlled, can lead cells to consume more than they should, degrading not only damaged components, but also proteins and organelles essential for their functioning. Fasting, although beneficial, is a form of controlled stress that we subject our bodies to.
This stress can be extremely positive, improving cellular function and promoting overall health. However, it is essential to recognize that the ideal duration and amount of fasting varies from person to person. Finding the right balance where fasting offers benefits without causing harm is crucial.
Faced with this individuality in the practice of fasting, a fundamental question arises: in the absence of food, where exactly does our body obtain the energy necessary to sustain its vital functions? In this case, the body begins to seek alternative sources of energy in a meticulously orchestrated process. The first reserve to be accessed is the glycogen stored in the liver, a quick source of glucose to meet immediate energy needs.
However, the capacity of this reserve is limited, lasting approximately 24 to 36 hours. Once exhausted, the body reveals its adaptability by turning to other sources of energy. Muscles also store glycogen, which can be used for energy locally, although it is not as readily released into the bloodstream as liver glycogen.
When fasting continues for longer and we need more energy, the body uses another mechanism, and it is at this point that it starts to use body fat. This process is called lipolysis. Think of stored fat as a reserve of fuel that the body saves for times when food is unavailable.
During prolonged fasting, the body begins to break down this fat into two main parts: fatty acids and a substance called glycerol. When the body begins to break down stored fat, we enter a metabolic state called ketosis. During ketosis, the liver converts some of these fatty acids into molecules called ketone bodies.
These ketone bodies can cross the blood-brain barrier and serve as a vital source of energy for the brain, replacing glucose as its primary fuel. In addition to lipolysis and ketosis, the body employs another crucial mechanism to ensure continuous energy supply during prolonged fasting: gluconeogenesis. This process occurs mainly in the liver and, to a lesser extent, in the kidneys.
Gluconeogenesis transforms glycerol, from the breakdown of fat, and other non-carbohydrate substrates, such as amino acids, into glucose. It is at this point in the explanation that an important and often ignored question arises: how does this process affect people with very low body fat? Very thin people face a different scenario when their glycogen stores are depleted.
In the absence of fat reserves, our body, in a desperate act of survival, turns to a last resort: its own muscles. Imagine muscles, built with so much effort, slowly being dismantled piece by piece. Proteins, the building blocks of these vital structures, are broken down into amino acids no longer to build, but to be burned like firewood in an emergency fire.
Furthermore, in the long term, this survival strategy can negatively affect other essential bodily functions that depend on proteins, such as cell repair, production of hormones and enzymes, and maintenance of the immune system. Therefore, for individuals with very low body fat, fasting, especially if prolonged, requires careful consideration and often the guidance of a healthcare professional. Faced with these risks, some people choose metabolic fasting, an approach that differs from traditional physiological fasting, where all calories are restricted.
In metabolic fasting, healthy fats are strategically consumed to provide energy without significantly increasing insulin levels, thus maintaining the fasting metabolic response. However, this strategy requires metabolic adaptation, which can take time. As we explore the fascinating mechanisms by which the body adapts to the search for energy in the absence of food, another very important question arises: what about essential micronutrients, such as vitamins and minerals?
After all, these micronutrients support nearly every biological process, from immune function to bone health and hormonal regulation. The answer lies in another incredible survival mechanism: for example, the fat-soluble vitamins A, D, E, and K are stored in body fat and released as needed. This is an efficient strategy to ensure a continuous supply of these essential micronutrients, even during periods of fasting.
However, here we are faced again with the question we mentioned before: what about individuals with a low body fat index? For very thin people, the amount of fat-soluble vitamins stored may be naturally lower due to the reduced amount of fat. But that doesn't mean they will automatically face deficiencies in these micronutrients during short periods of fasting.
The body is able to regulate the release of these vitamins. However, this issue further highlights the importance of a diet rich in micronutrients outside of fasting periods and the need for care when intending to fast for longer periods. Some individuals may need supplementation or dietary adjustments to ensure adequate intake of these essential nutrients.
But in addition to fat-soluble vitamins, there are several other micronutrients that support the proper functioning of the body as a whole. Imagine the human body as a symphony orchestra, where each micronutrient has its unique role, contributing to the harmony of the music of life. During the fast, this orchestra faces the challenge of continuing its symphony, even when instruments, or in this case, nutrients, seem scarce.
Calcium, the maestro of bone health and muscle contraction, finds itself in a delicate dance, balancing between the bones and the blood during times of fasting. The body skillfully directs calcium from the bones to maintain blood levels, ensuring the music doesn't stop. However, as any great conductor knows, it is essential that the orchestra is replenished, indicating the importance of calcium-rich nutrition during fasting intervals to keep bones strong and music vibrant.
Iron and zinc, the virtuosos of the orchestra, responsible for the vitality of red blood cells and strengthening the immune system, are masterfully recycled by the body. They are removed from old cells and reintroduced into the bloodstream, a symphony of efficiency that ensures these minerals continue to contribute to overall health. B complex vitamins, the keys that keep energy metabolism at an accelerated pace, and phosphorus, essential for creating the score of life in the form of ATP, are kept in harmony through careful management of bodily resources.
The body ensures that, even in food silence, the music of metabolism continues. In addition to calcium, iron, zinc, B vitamins, phosphorus, and other virtuoso musicians such as magnesium and sodium, and a variety of other micronutrients, there is one element without which our bodily symphony orchestra could not exist: water. Imagine water as the invisible conductor, whose baton guides the harmonious flow of nutrients through our organism.
Hydration is not only vital to sustaining life; it is the means by which each nutritional note reaches its fullness, allowing vital processes to occur, from facilitating the circulation of nutrients to the efficient removal of waste. Just as an orchestra depends on a solid stage and an attentive conductor for its performance, our bodies depend on hydration to keep the health tune resonating. Therefore, during and after fasting, it is essential to not only replenish our body with micronutrients, but also ensure adequate hydration, keeping the music of life in its richest harmony.
As the symphony of micronutrients continues to resonate in our bodies, revealing the intricate beauty of life in each cell, it is crucial that we remember a fundamental truth: each individual is a unique universe, with distinct needs and responses to fasting. The practice of fasting, although it is a powerful controlled stress capable of strengthening the body at a cellular level, does not follow the maxim of "the more, the better". On the contrary, she sings the melody of balance, moderation, and adaptation.
