Intermittent fasting: everything you need to know about this practice

Who I am
Robert Maurer

More and more often we hear about intermittent fasting, but what is it specifically and what are the real benefits of this practice?

In this new episode of the column on Biohacking

So let's find out in detail this practice and how it can help you hack your well-being and your vitality.


Over the past fifteen years, intermittent fasting has become incredibly popular as a tool for reduce weight and improve the metabolic health.

Animal studies have also suggested a potential increase in longevity.

Until recently, however, the topic was the preserve of independent researchers and fitness gurus looking for a fat-burning strategy.

However, in recent years things have changed and so has the New England Journal of Medicine - the most prestigious scientific journal in the world - the December 26 2019 published a review showing how this practice can significantly improve health.

Maybe it was the guilt of the Christmas lunch?! ;-)

According to the Prof. Mattson, author of the publication, unfortunately general practitioners still do not recommend this regimen, mainly due to their limited knowledge of the subject.

That's why we decided to deepen the topic and share its many benefits with you.

Let's start with an essential clarification ...

What is intermittent fasting and why you need to try it

Intermittent fasting is not a diet.

Instead it represents a new way of plan meals in order to get the maximum benefit from food.

Like? Alternating throughout the day periods of fasting e supply in different relationships than those we are used to.

Usually between dinner and the following breakfast - break-fast meal, from the English break (break), fast (fast) - they spend on average 10-12 hours.

Practicing intermittent fasting simply means lengthen the fasting window between dinner and breakfast by a few hours - something very different from the prolonged abstention from food proposed in some specialized clinics.

Furthermore, based on your needs (weight loss, sports performance, focus and productivity, etc.) you can decide whether:

  1. Anticipate dinner.
  2. Delaying breakfast.
  3. Combine meals.
  4. Eliminate one of the two meals (dinner or breakfast) to also get a calorie restriction.

It is not about changing what you eat but when you eat

Over the centuries humans have practiced fasting for religious reasons or for food shortages. So much so that our body has developed numerous adaptive mechanisms that have allowed survival during times of famine. For this reason, intermittent fasting is usually well tolerated and has no particular contraindications.

Experiments on mice showed that by letting the rodents free to eat what they wanted for a limited time (6-8 hours), the subsequent fasting condition (16-18 hours) conferred protection against weight gain and damage. food.

No, of course I'm not recommending you binge on McDonald's sandwiches and then make up for it with a few hours of fasting. I just want you to understand the power of the simple hourly restriction: concentrate all meals in a limited time window it can have extraordinary effects.

The benefits of intermittent fasting

Here are a series of benefits that we can obtain simply by changing the timing of our meals:

  • Promotion of the weight loss - and in particular body fat - regardless of the calories introduced.
  • Activation ofautophagy, an important cellular "cleaning" mechanism at the basis of health and longevity.
  • Increase ofphysical energy e mental.
  • Improvement of the relationship with food: voluntary restriction leads to eating slowly and savoring food more.
  • Optimization of cognitive functions with benefits on mood and memory.

Do you think that to improve mental processes the philosopher Pythagoras he required students to fast before receiving his teachings. This was many centuries before science demonstrated the ability of fasting to stimulate the activity and growth of neurons.

Instead there is no need for a publication to state that intermittent fasting you create time e increase productivity because it greatly simplifies our days and reduces the time we dedicate to preparing and taking meals.

Then experiment with which form of intermittent fasting is best suited to your needs and lifestyle (remember the four variants I told you about a few paragraphs ago?) also promotes a pleasant side effect: theself-awareness, understood as the ability to observe and pay attention to oneself.

Being fully present in everything you do helps you recognize your body's signals and gather valuable information about its functioning.

How intermittent fasting works

During periods of fasting, the body changes the way it produces energy, passing from the use of sugars to the conversion of fatty acids into chetonic bodies which thus become the main fuel for most organs, including the brain.

This metabolic switch, if activated periodically, has a series of health benefits, since ketone bodies, in addition to being fuel for the cells, also represent powerful signal molecules for specific physiological functions.

Activating this switch can improve:

  • I metabolic parameters (eg blood sugar).
  • La resistance to stress.
  • I levels of tissue inflammation (deleting them).

"The best medicines are rest and fasting."

Benjamin Franklin.

Metabolic flexibility can affect your mental flexibility

Your identity and yours personality they depend on many factors, but one of them is certainly yours energy level.

Feeling vital throughout the day thanks to the application of these dietary protocols literally transforms who you are.

If you change the way you eat, you change the flow of energy in your body. This has an effect on your feelings, your thoughts and consequently your behaviors.

Yes, we can therefore say that the intermittent fasting it potentially changes your choices, your ambitions and your potential.

"Fasting for greater physical and mental efficiency."


And if you think you can't fast for 16 consecutive hours just think that we would not be here if our ancestors had not resisted without food for several days.

So test your eating habits and, once the initial mental resistance has been overcome, you will notice that meal times at the end are simple conventions that we can do without.

Besides, do you know why we eat three meals a day? The answer is not written in science books but in food industry marketing manuals ...

There is no one way to do intermittent fasting

There are many protocols that can be followed, from fasting every other day to OMAD (One Meal A Day - one meal a day).

However, I will focus on a single style, the most practical one and which is supported by the greatest number of scientific studies: fasting 16/8.

This form is very simple to apply, in fact it requires you to select one 8-hour window in which to consume your calories and fast for the rest of the day.

It should be made clear that although it is easy to obtain a calorie restriction as well, this is in reality not necessary.

The most important thing of all is to respect the timing of meals: a simple precaution capable of improving the metabolism and the hormonal structure.

Many people unconsciously practice intermittent fasting by skipping breakfast, but personally I prefer to have my dinner before 18pm. In this way I respect my parents more. circadian rhythms, I improve the quality of mine sonno and second the popular wisdom, always full of great teachings.

"Breakfast like a king, lunch like a prince, dinner like a poor man."

Ancient Proverb.

Numerous studies have also shown that blood sugar control is better during the day than in the evening, as well as the functioning of digestive enzymes and the amount of calories burned.

Not to mention sleep, which I mentioned to you: how many times do you rest badly after eating too much and too late?

This habit subjects the organs of the digestive system to a stress comparable to jet lag because it forces them to overwork at times when they are programmed to rest.

First steps: how to do intermittent fasting

Practicing intermittent fasting every day is not a convenient solution, in fact, as with any stimulus provided to our body it is preferable to have a certain variability.

You can start by choosing one day per month and then one per week, up to a maximum of three days a week.

I also recommend starting gradually by tightening the "food window" first to 12 hours, then to 10 and finally to 8 hours.

It is also important to establish based on your goals, possibly with the help of a professional, if there should also be a calorie restriction, without becoming too rigid on the foods to choose.

Intermittent fasting is a form of dietary freedom, provided of course you maintain a balanced diet.

An answer to your doubts

1) During intermittent fasting I will have to stay in the chair or I will be able to lead one normal life working e training?

The answer is yes, you can have an absolutely normal life and train, in fact, regardless of the calorie intake usually the energy level remains intact or even tends to increase.

Science has made it clear that a minimal reduction in energy levels is observed after at least 24 hours of prolonged fasting. For this reason do not limit yourself and indeed take advantage of the time gained for lead the day actively.

The only obstacle you might contend with is there fame.

Let me be clear, it will be "mental" and not physical hunger, so not an emergency but a signal that the body sends when it expects food. Usually, however, after the first few weeks of meal flexibility this tends to disappear.

2) I can drink tea e coffee during the fasting phase?

Although they are xenobiotic, that is substances foreign to our body, they do not affect fasting that much, provided that they are taken without sugar or milk. A separate discussion for water, the consumption of which these days should be increased to facilitate cell detoxification processes.

3) What to eat immediately after the end of the fast?

It is recommended that the next meal be sano ed balanced, avoiding elaborate dishes, alcohol and carbohydrates with a high glycemic index.

Fasting: a gender issue

Before closing this discussion, I think it is important to make a clarification that is often underestimated when it comes to intermittent fasting.

Indeed, we must know that women respond to intermittent fasting differently than men.

For an evolutionary reason linked to the reproduction of the species, the female organism is more sensitive than the male one to the signs of "famine".

This means that when the restriction is implemented in a rigid and frequent way it risks negatively affecting the hormonal responses e behavioral. However, this should not discourage because with small tricks even women can access the numerous benefits of this practice. In particular, I recommend:

  • Avoid fasting during the pregnancy andnursing.
  • Prefer the days following the menstrual flow and not the ovulatory phase.
  • Proceed in gradually and prefer thefood intake early in the day (translated: do not skip breakfast, but rather anticipate or skip dinner).
  • Don't practice high intensity physical activity during the first few attempts.


Intermittent fasting is much easier to follow than either restrictive diet and it has all it takes to become a long-term habit.

Its potential goes beyond the nutritional and metabolic aspect, in fact by definition fasting is one of the useful tools to stimulate thehormesis: the administration of a stressor (absence of food) which in the right dose activates an adaptive response and makes us stronger and healthier.

However, when a stressor becomes chronic, he loses his positive characteristics and can potentially harm us.

The advice, therefore, is, and I repeat, that of proceed gradually, experiment with the time window more compatible with your lifestyle and look for the ideal frequency of execution of the fast. The benefits will not be long in coming!

“Study science first, and then practice, born of science, followed. Those who fall in love with practice without science are like the helmsman who enters a ship without a rudder or compass, who is never sure where he is going. "

Leonardo da Vinci.

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