<\/p>\n
Yet, For most of human history, the absence of food was not an exception<\/strong>:<\/p>\n it was a normal physiological condition.<\/p>\n <\/p>\n Fasting is not born as a technique, nor as a challenge, it is born as a space.<\/p>\n <\/p>\n Space in which the body, finally, doesn't have to deal with introducing, digesting,<\/p>\n store and can go back to doing what it's designed for: to maintain oneself<\/strong>.<\/p>\n <\/p>\n The word \"digiuno\" (fasting) comes from the Latin \"ieiunus,\" meaning empty, free from food.<\/p>\n But \u201cempty\u201d in this case doesn't mean a lack.<\/p>\n Means no load<\/strong>.<\/p>\n Even ancient civilizations realized that, at certain times, taking away is more powerful than<\/p>\n Add.<\/p>\n <\/p>\n Hippocrates<\/strong> observed that during illness, the natural instinct is not to eat:<\/p>\n not out of weakness, but because the body redirects the Energy towards healing<\/strong>.<\/p>\n <\/p>\n Modern science has only given a biochemical name to this intuition.<\/p>\n <\/p>\n One of the most common misunderstandings is thinking of fasting as a clear-cut event:<\/p>\n You eat, or you don't eat.<\/p>\n Actually, fasting is a physiological progression, an orderly sequence of adaptations. In the first few hours, the body simply finishes what it was doing: digesting.<\/p>\n Then, gradually, change strategy.<\/p>\n <\/p>\n In the hours following the last meal, the body is in a state defined as post-prandial:<\/p>\n - <\/span>relatively high insulin<\/strong><\/p>\n - <\/span>glucose as the main energy source<\/strong><\/p>\n - <\/span>storage-oriented metabolism<\/strong><\/p>\n <\/p>\n When the meal is fully digested and absorbed, insulin begins to drop.<\/p>\n This passage is crucial.<\/p>\n <\/p>\n - <\/span>remove the buildup signal<\/p>\n - <\/span>allows lipolysis activation (release of fatty acids from adipose tissue)<\/p>\n - <\/span>Signal the liver to begin producing endogenous glucose (gluconeogenesis)<\/p>\n At this stage, the body is not yet in deep fasting, but it is changing its system.<\/p>\n <\/p>\n When liver glycogen stores begin to decrease, the body must make a metabolic decision:<\/p>\n continue to depend on glucose or become more flexible.<\/p>\n This is where the real paradigm shift occurs.<\/p>\n <\/p>\n The body increases fatty acid oxidation and begins to produce ketone bodies<\/strong> in the liver.<\/p>\n Ketones are not an \u201cemergency fuel\u201d: they are a highly effective energy source<\/p>\n efficient, especially for the brain.<\/p>\n <\/p>\n At the same time, autophagy is activated more evidently, an intracellular recycling process regulated by energy sensors such as:<\/p>\n - <\/span>AMPK (energy sensor)<\/p>\n - <\/span>mTOR (nutritional abundance sensor)<\/p>\n <\/p>\n When mTOR is inhibited and AMPK is activated, the cell enters maintenance mode:<\/p>\n - <\/span>Damaged proteins are disassembled<\/p>\n - <\/span>Inefficient mitochondria are eliminated<\/p>\n - <\/span>Obsolete components are recycled.<\/p>\n <\/p>\n It's not destruction: it's quality.<\/p>\n <\/p>\n If the fast continues, the body demonstrates one of its most sophisticated capabilities:<\/p>\n <\/p>\n selective protection of noble tissues.<\/p>\n <\/p>\n In this phase:<\/p>\n - <\/span>growth hormone (GH) increases<\/strong><\/p>\n - <\/span>Protein turnover is reorganizing<\/strong><\/p>\n - <\/span>Muscle mass is largely preserved<\/strong><\/p>\n - <\/span>The brain uses more and more ketones, reducing the need for glucose.<\/strong><\/p>\n <\/p>\n Fasting does not automatically lead to muscle loss.<\/p>\n Actually, in the correct context, the body defends muscle tissue because it is essential for survival.<\/p>\n <\/p>\n Starting at 48 hours, fasting enters a more therapeutic rather than nutritional dimension.<\/p>\n Observed:<\/p>\n - <\/span>reduction of inflammatory markers<\/strong><\/p>\n - <\/span>improving insulin sensitivity<\/strong><\/p>\n - <\/span>Increased mitochondrial biogenesis<\/strong><\/p>\n - <\/span>greater efficiency of the respiratory chain<\/strong><\/p>\n <\/p>\n The body is not in \u201cblind saving mode,\u201d but in optimization mode.<\/p>\n <\/p>\n After 72 hours in controlled and non-universal contexts, autophagy becomes systemic and some studies show a reorganization of immune cells and endocrine signals<\/strong>.<\/p>\n It's not necessary to reach that point to achieve benefits: it's simply a demonstration of how well the body can adapt.<\/p>\n <\/p>\n When fasting continues and ketone bodies increase (especially beta-hydroxybutyrate, BHB), the brain receives not only an alternative fuel but also a signal.<\/p>\n BDNF and neuroplasticity<\/p>\n BDNF (Brain-Derived Neurotrophic Factor) is a \u201ctrophic protein\u201d: a molecule that supports the growth, survival, and connections of neurons. In simple terms: it helps the brain adapt and learn.<\/p>\n <\/p>\n In various studies, metabolic states associated with fasting<\/strong> Each other ketosis<\/strong> show an increase in signals related to neuronal plasticity. The reason is consistent with evolutionary logic: In times of food scarcity, a brighter and more adaptable brain increases survival chances.<\/strong>.<\/p>\n <\/p>\n The brain can use BHB as an energy source; many people perceive this as increased mental clarity. It's not magic: it's a fuel switch with different energy and hormonal dynamics.<\/p>\n <\/p>\n With low insulin and more stable availability of energy substrates (fatty acids + ketones), the system can become more \u201cstable,\u201d with fewer peaks and crashes. In many individuals, though not all, this translates into a feeling of greater mental continuity.\ud83d\udc49 <\/span>In summary: fasting can become a context in which the brain operates with more stable energy and with pro-adaptation signals (BDNF\/neuroplasticity), especially when ketogenesis is active.<\/p>\n <\/p>\n During fasting, changes occur that primarily concern mitochondrial quality.<\/p>\n 1) AMPK: the low energy sensor AMPK (AMP-activated protein kinase) is a biochemical \u201cswitch\u201d that turns on<\/p>\n when available energy is low. When AMPK rises, the cell shifts its focus to:<\/p>\n <\/p>\n - <\/span>efficient energy production<\/p>\n - <\/span>saving non-essential processes<\/p>\n - <\/span>activation of repair mechanisms<\/p>\n <\/p>\n Autophagy means \u201cself-eating\u201d: the cell recycles damaged components.<\/p>\n Mitophagy is a specific subprocess: it eliminates dysfunctional mitochondria.<\/p>\n This is crucial: it's not enough to have many mitochondria; they need to be good.<\/p>\n Fasting can promote this internal \u201cnatural selection,\u201d increasing the proportion of more efficient mitochondria over time.<\/p>\n 3) PGC-1\u03b1 and mitochondrial biogenesis PGC-1\u03b1 is a regulator that promotes the creation of new mitochondria and adaptation<\/p>\n Oxidative. Fasting + light exercise can enhance signals that lead towards a greater capacity to oxidize fats and produce ATP in an orderly manner.<\/p>\n <\/p>\n \ud83d\udc49 <\/span>In summary:<\/strong> Fasting is not just \u201cless energy,\u201d but often more efficient energy<\/strong>,because it improves mitochondrial quality control (mitophagy) and promotes oxidative adaptations.<\/p>\n <\/p>\n The liver is the \u201cmanagement center\u201d of fasting.<\/p>\n <\/p>\n Initially, it uses glycogen (glucose reserve). Then it produces endogenous glucose<\/p>\n (gluconeogenesis) from precursors such as lactate, glycerol, and some amino acids.<\/p>\n It's a controlled process: it serves to maintain glucose for tissues that need it most.<\/p>\n <\/p>\n When insulin is low and free fatty acids increase, the liver produces ketones. This<\/p>\n a way to export \u201cconcentrated\u201d energy to the brain, muscles, and other tissues.<\/p>\n <\/p>\n Fasting and reducing meal frequency can improve insulin sensitivity<\/p>\n (that is, the cells' ability to respond to insulin). In practice: less insulin<\/p>\n necessary for the same effect, in many people.<\/p>\n <\/p>\n \ud83d\udc49 <\/span>In summary:<\/strong> The liver is the director that makes fasting sustainable, shifting from food management to reserve management, with often favorable effects on insulin and metabolic flexibility.<\/p>\n <\/p>\n Immune System: Reprogramming and Noise \u201cCleanup\u201d\u00a0<\/b>inflammatory<\/b><\/p>\n <\/p>\n It's important to be precise here: fasting doesn't \u201cboost\u201d immunity indiscriminately.<\/p>\n <\/p>\n Rather, in some contexts it can reduce inflammatory noise and promote regenerative processes.<\/p>\n <\/p>\n - <\/span>Reduction of pro-inflammatory signals related to overfeeding and high insulin<\/p>\n - <\/span>Support for cellular turnover processes through autophagy<\/p>\n - <\/span>Possible improvement of certain immunometabolic dynamics (interaction between metabolism and immunity)<\/p>\n <\/p>\n \ud83d\udc49 <\/span>In summary:<\/strong> less \u201cbackground noise,\u201d more order. Not a superpower, but a normalization.<\/p>\n The point isn't that fasting is magical.<\/p>\n <\/p>\n It's that it momentarily removes the \u201cnoise\u201d of continuous abundance, and allows the body to activate programs that - by design - emerge when adaptation is needed:<\/p>\n <\/p>\n greater mitochondrial efficiency, more metabolic order, and often a more\u00a0Stable and plastic.<\/span><\/p>\n <\/p>\n From a physiological standpoint, fasting only works if:<\/p>\n <\/p>\n - <\/span>is not perceived as a threat<\/strong><\/p>\n - <\/span>is not associated with chronic stress<\/strong><\/p>\n - <\/span>it is included in a recovery context<\/strong><\/p>\n <\/p>\n This is why a gradual approach is essential:<\/p>\n <\/p>\n - <\/span>progressively extend the night window<\/strong><\/p>\n - <\/span>Start with intermittent fasting<\/strong><\/p>\n - <\/span>Improve sleep and diet quality<\/strong><\/p>\n <\/p>\n A fast that worsens energy, mood, and recovery is not yet the right fast.<\/p>\n <\/p>\n So, in practical terms:<\/p>\n <\/p>\n it makes sense to start with short intermittent fasts<\/strong>, gradually extending them over time (e.g., 10, 12, 14\u201316 hours), allowing the body time to adapt.<\/p>\n <\/p>\n Only when these intervals are well tolerated \u2014 without marked drops in energy, concentration, or well-being \u2014 can one consider, if desired, a 24-hour fast.<\/p>\n <\/p>\n For further extensions (30, 36, or up to 48 hours), is prudent<\/strong> wait a few weeks between each attempt, observing how the body reacts in the following period: sleep, hunger, mood, physical and mental performance. Each new step must be re-evaluated based on previous experience, not on a predetermined goal.<\/p>\n <\/p>\n Fasting should be broken in the presence of marked stress signals or dysfunction (persistent weakness, dizziness, mental confusion, rapid heartbeat, marked worsening of sleep or mood).<\/p>\n <\/p>\n May<\/b> continue a fast just for\u201creach a set duration<\/b>\u201dif the body is<\/p>\n clearly signaling to stop. In that case, you're not stimulating adaptation,<\/b><\/p>\n but accumulating stress.<\/b><\/p>\n <\/p>\n From an evolutionary standpoint, fasting never occurred while stationary. Light movement during fasting:<\/p>\n <\/p>\n - <\/span>improve fat oxidation<\/strong><\/p>\n - <\/span>enhance AMPK activation<\/strong><\/p>\n - <\/span>Strengthen adaptation signals<\/strong><\/p>\n - <\/span>Communicate to the body, \u201cI am capable, I am not in danger.\u201d<\/strong><\/p>\n <\/p>\n <\/p>\n After a fasting period, the digestive and metabolic systems are more sensitive.<\/p>\n From an endocrine perspective, it is the moment when it is decided whether:<\/p>\n <\/p>\n - <\/span>gradually return to equilibrium<\/strong><\/p>\n - <\/span>to create an unnecessary shock<\/strong><\/p>\n <\/p>\n High-quality protein, moderate portions, and simple foods allow for:<\/p>\n <\/p>\n - <\/span>a controlled insulin response<\/strong><\/p>\n - <\/span>an orderly overview of protein synthesis<\/strong><\/p>\n - <\/span>A smooth transition out of fasting<\/strong><\/p>\n <\/p>\n What do you think?<\/p>\n Have you tried it?<\/p>\n Did you feel like trying it?<\/p>\n Let's talk about it, I'm reading you!<\/p>\n <\/p>\n Thank you<\/strong> For your attention,<\/p>\n Always grateful.<\/p>\n Oliver<\/strong><\/p>","protected":false},"excerpt":{"rendered":" Viviamo in un\u2019epoca in cui mangiare \u00e8 diventato continuo, automatico, quasi\u00a0inconsapevole. Eppure, per la maggior parte della storia umana, l\u2019assenza di cibo non era un\u2019eccezione: era una condizione fisiologica normale. Il digiuno non nasce come tecnica, n\u00e9 come sfida, nasce come spazio. Spazio in cui il corpo, finalmente, non deve occuparsi di […]<\/p>\n","protected":false},"author":7,"featured_media":29705,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"inline_featured_image":false,"footnotes":""},"categories":[106,119],"tags":[],"class_list":["post-29702","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-alimentazione","category-digiuno"],"_links":{"self":[{"href":"https:\/\/cristinatomasi.com\/en\/wp-json\/wp\/v2\/posts\/29702","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cristinatomasi.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cristinatomasi.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cristinatomasi.com\/en\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/cristinatomasi.com\/en\/wp-json\/wp\/v2\/comments?post=29702"}],"version-history":[{"count":0,"href":"https:\/\/cristinatomasi.com\/en\/wp-json\/wp\/v2\/posts\/29702\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/cristinatomasi.com\/en\/wp-json\/wp\/v2\/media\/29705"}],"wp:attachment":[{"href":"https:\/\/cristinatomasi.com\/en\/wp-json\/wp\/v2\/media?parent=29702"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cristinatomasi.com\/en\/wp-json\/wp\/v2\/categories?post=29702"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cristinatomasi.com\/en\/wp-json\/wp\/v2\/tags?post=29702"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}An ancient word for an ancient function<\/b><\/h3>\n
Fasting is not a single state, but a process<\/b><\/h3>\n
The first 12 hours: end of the postprandial phase<\/b><\/h3>\n
Insulin reduction:<\/h4>\n
Between 6 PM and midnight: fuel change and activation\u00a0<\/b>of autophagy<\/b><\/h3>\n
\ud83d\udd39<\/span> Metabolic flexibility<\/b><\/h3>\n
\ud83d\udd39<\/span> Autophagy<\/b><\/span><\/h3>\n
Around 36 hours: systemic adaptation and savings\u00a0<\/b>intelligent<\/b><\/h3>\n
This is a key point that is often misunderstood:<\/h4>\n
48 hours and beyond: profound reorganization of signals\u00a0<\/b>cell phones<\/b><\/h3>\n
What do organs actually receive from fasting<\/b><\/h3>\n
Brain: BDNF, neuroplasticity, and \u201ccleaner\u201d fuel\u201d<\/b><\/h4>\n
2) Ketones as efficient fuel<\/h4>\n
3) Fewer blood sugar fluctuations<\/h4>\n
Mitochondria: efficiency, quality, and energy \u201ccleanliness\u201d<\/b><\/h3>\n
2) Autophagy and Mitophagy: Internal Maintenance<\/h4>\n
Liver and Metabolism: Endogenous Glucose, Ketogenesis, and Sensitivity\u00a0<\/b>insulinica<\/b><\/h3>\n
1)<\/strong> From glycogen to gluconeogenesis<\/h4>\n
2)<\/strong> Ketogenesis: production of ketone bodies<\/h4>\n
3)<\/strong> Insulin sensitivity<\/h4>\n
How to approach fasting without triggering unnecessary stress<\/b><\/h3>\n
The central aspect always remains one: listening to the body's signals.<\/b><\/h3>\n
Movement during fasting: an evolutionary signal, not\u00a0<\/b>a contradiction<\/b><\/h3>\n
Walking, moving, and breathing deeply do not break your fast:\u00a0<\/b>the complete one.<\/b><\/h4>\n
Breaking the fast: reactivating without overloading<\/b><\/h3>\n