Intermittent fasting: everything you need to know –

O intermittent fasting which aims mainly at slimming may even be a practice of this century. But not the fast itself. The concept is thousands of years old, and most of the time it was related to the spirituality: Religions such as Judaism, Christianity, Hinduism, Islam and Buddhism have always used it for different purposes (penance, conciliation, purification, spiritual development…).

The logic behind all types of fasts millennials is basically the same — cut what is it? toxic for the mind and body. “It is one of the oldest and most widespread healing traditions in the world. The most famous are the forty days of Moses and Elijah. Hippocrates of Kos (460-370 BC), considered the father of modern medicine, also defended the practice”, exemplifies nutritionist and holistic therapist Will Powa (@powahealthyfood).

The specialist is even one of the great defenders of the custom. “In my experiences with 24h or longer protocols, I feel great mental relief, lowered anxietystrong spiritual connection and deep peace.”

The thing is, it doesn’t stop there. Science, for some years now, has been studying the effects of fasting in relation to different objectives: slimming, reduced risk of chronic diseases and even cancer prevention. And since the modern strategy involves interspersed periods of abstinence and eating, like a cycle, it has a second name — intermittent.

How does intermittent fasting work?

Endocrinologist Lorena Lima Amato (@dra. lorenaendocrino), from SBEM (Brazilian Society of Endocrinology and Metabology), explains that after a few hours without food, our organism begins to use the glycogen (mainly located in the liver) as a source of energy, turning it into glucose. When stores in the organ get too low (usually after 8 hours), the body needs to find other fuel to keep it going.

There, he bets on fatand enters the so-called stage of ketosis. “This benefits weight loss, the reduction of visceral fat and the improvement in insulin sensitivity”, lists nutritionist Luciana Harfenist (@lucianaharfenist).

And one thing leads to another. By decreasing the percentage of body fat, the dietary strategy helps to reduce bad cholesterol, as well as to improve heart rate and blood pressure. The drop in blood glucose also reduces the chances of developing diabetes.

Intermittent fasting phases and protocols

By adopting the technique, some somewhat unpleasant initial symptoms may appear, such as irritation, fatigue, excessive hunger and lack of concentration, signs that usually appear in the first days after adopting calorie-restricted diets. Weight loss with intermittent fasting also goes through some stages. Luciana explains:

First two weeks: shock phase, with sudden weight loss;
Between the 3rd and 10th week: adaptation phase, when weight loss begins to slow down due to increased cortisol and a drop in some hormones;
From the 12th week: plateau phase, with weight stagnation. To avoid this step, many professionals recommend alternating periods of intermittent fasting with periods of normal feeding.

– (artJazz/Disclosure)

There is not only one way to adopt it, but different protocols:

Also known as 16/8 method, is one of the best known. In it, you go without eating for 16 hours, and eat for the remaining 8. “It is allowed to have two or three meals, respecting your hunger. Drinking water, coffee and any other non-caloric drink is also a good idea”, says nutritionist Elifas Rodrigues (@drelifas), from the Benessere clinic.

Considered a slightly more moderate version. Twice a week, you only consume 500 calories a day. In the remaining five days, you can bet on a balanced diet. “Interesting for those who find it difficult to fast. But we must pay attention to the compensatory mechanism”, says nutrologist Vinícius Aguilera (@dr. vinicusaguilera), from the Aguilera Clinic. In other words, there is no point in ‘compensating’ periods of hunger with overeating — only 1500 calories are released per day.

The most extreme of all. You fast for long hours (12, 24 and even 36) and eat for 12 hours. “As the amount of calories consumed tends to be very low, weight loss is faster for those who practice this method. But he should be accompanied by a professional, because not everyone can go through such a caloric restriction”, advises nutrologist Alisson Melo (@dralissonmelo), from the Benessere Clinic.

The method consists of fasting (or eating very little) for a period of 20 hours, and then eating for the other 4 hours. “During the 20 hours, small amounts of dairy products, hard-boiled eggs, fruits, raw vegetables and non-caloric liquids can be consumed”, explains nutritionist Natalia Barros (@nataliabarros. nutri).

Here, the right thing is to stay 24 hours without food twice a week. The caveats are: do not do it on consecutive days or go a whole day without a meal. Example: you have breakfast and lunch until 2 pm, fast, and eat normally from 2 pm the next day.

Intermittent fasting: real case

Dani Serres (@daniserres) is one of those athletes who love a good challenge. She collects evidence: she has already completed five marathons, a half Ironman and has lost count of how many races she has done throughout her life. In one of her preparation periods (2015), she decided to bet on low carb diet to try to lighten up and endure 42 km in Chicago.

The combination of intense workouts and drastic reduction of carbs on the menu didn’t work well for Dani — her kidneys were overloaded and she had a suspicion of rhabdomyolysis (degradation of muscle tissues). So, he had to change his eating strategies, he cut the gluten and did the intermittent fasting. “I always felt that the digestion process required a lot of energy from my body. I decided to start with the 16-hour protocol — it’s the easiest for me,” she says.

Since then, he defends fasting tooth and nail. She only needed to take a break in the first few months of the pandemic because she wanted to focus on other aspects of her life. “I suffered a spinal injury (due to training on the treadmill at home without monitoring) and I was out of action for months. I also started drinking more often. That meant a few extra pounds on the scale.”

Dani knew she wanted to get back on the nutrition plan. Therefore, she decided to opt for a variation of the eat-stop-sleep method even bolder: instead of going two days a week without eating, I would go three (Mondays, Wednesdays and Fridays). “I lost 14 kilos that way.”

Dani at the beginning of the pandemic / Dani now (Dani Serres/Personal collection)

Today, she does two fasts a week, one for 24 hours, and another for 16. And she swears that the benefits go far beyond weight loss. “The feeling is body detoxification. Also, I learned to identify (and deal with) true hunger, and to enjoy my meals much more. When I’m close to break the fastI make a point of cooking my dish with care and affection.”

How to break food abstinence, incidentally, is something that should be very well thought out. “You need to eat the equivalent of one meal. And not all day long”, advises the runner and nutrition student, who also says she doesn’t feel any damage to her performance. “On fasting days, I try to do lighter runs or weight training. And I always program myself for the breakdown to happen right after I work out. In this way, I prepare post workout snack careful to avoid loss of muscle mass.”

Intermittent fasting contraindications

But of course, what worked for Dani might not work for others. The contraindications of intermittent fastingincluding, there are many. Starting with:

1 – Pregnant and lactating women

“They don’t just have themselves to feed. Therefore, they need to eat several times a day, and focus on healthy items”, says endocrinologist Cristiano Barcellos (@drcristianobarcellos), by SBEM.

“Diabetics (type I or II) who are also insulin dependent suffer great risks of hypoglycemia (sudden drop in blood sugar)”, says endocrinologist Guilherme Renke (@endocrinorenke). On the other hand, those who have type II diabetes and do not use insulin as a treatment can benefit from fasting, as long as they are accompanied by a doctor.

3 – People with eating disorders

Although studies demonstrate that the intermittent fasting does not aggravate frames of binge eating already controlled, the official position of the specialists, explains Cristiano Barcellos, is not to recommend it for those with a history of some type of disorder. “If we are going to balance the risks and benefits, it is not a good indication”, adds Guilherme Renke.

As we age, we naturally and progressively lose lean body mass, a process called sarcopenia. “And this, added to a lower supply of nutrients due to fasting, can aggravate the problem, generate inflammation in the body and stimulate the production of hormones that prevent muscle growth. All factors increase the risk of death”, emphasizes the SBEM endocrinologist.

What Science Knows About Intermittent Fasting

Research has investigated the effects of fasting on laboratory mice. One of them, published in the journal Naturefor example, showed that mice that did not eat for 24 hours had increased efficiency of the P21 gene — an important tumor suppressor.

– (Eleonora Grigorjeva/Getty Images)

Now, we need to find out if the same happens to humans. “The tested animal lives for two years, and we much longer — therefore, the time is different for the two groups. So, to obtain the same advantages observed in rodents, we would need to fast much longer than one day”, comments Cristiano Barcellos.

Other results are just as encouraging: there is even talk of decreased severity of coronavirus symptoms. But the studies are still in very early stages. “More research is needed, especially with regard to long-term results,” says nutritionist Natalia Barros.

A sustainability this type of diet is also a topic that needs further investigation. After all, Natalia says that the practice is not at all easy to take for life. “Some articles say that those who do intermittent fasting generally do not maintain it compared to those trying to lose weight on more traditional diets.”

But what’s the verdict on intermittent fasting?

that the intermittent fasting is a valid strategy to lose weight, lose body fat and lower the risks of chronic disease, experts seem to agree. But the method isn’t safe for everyone, and its advantages don’t go far beyond those offered by any other calorie-restricted diet—as far as science is concerned.

“When we compare the intermittent fasting with…