experts disagree on whether or not the practice is recommended

A practice that has become a real fever among the population that wants to lose weight, the intermittent fasting It is a subject that polarizes opinions. Health experts often disagree on whether the measure is advisable or not. The activity consists of going long periods without eating to help with weight loss. Initially, the feeding time can be restricted to 8 hours, but it can reach 12, 16 or even 24 hours, in a more extreme way.

Professor of the endocrinology and metabolism service at Hospital de Clínicas de Porto Alegre (HCPA) and professor at Ufrgs, Fernando Gerchman, is one of the specialists who usually recommend intermittent fasting as a diet. For the professional, the practice is safe, but contraindications exist and can be evaluated by consulting. “There are patients that you don’t want to do (the follow-up), that you think the patient will not be able to have a good acceptability. And then a hypocaloric diet (low-calorie menu) can be recommended, which has no time restriction” , emphasizes.

For clinical nutritionist Cintia Squeff, intermittent fasting is more likely to cause problems than benefits. “To do this type of fasting, the person has to be very healthy. It is an attack treatment, you have to trust the patient a lot. It’s dangerous, kind of risky to do”, she explains. The expert says that she recently witnessed a woman fall for being dizzy after going 16 hours without food. “It (fasting) can give you dizziness, lack of concentration, bad mood,” she points out.

Production Engineering student Kethlin Cruz, 22, found out about intermittent fasting on YouTube. She has been using the practice for two years and claimed to feel good, with a loss of up to 9 kilos in conjunction with a diet. According to her, the measure is only useful if she takes care of food within the available times to eat, the so-called food window. “When I’m not following any diet, that is, I’m eating normal and I decide to fast, I see that it gives me that push for binge episodes. When I’m in the eating window, I exaggerate and end up eating everything I didn’t eat during the while I was fasting. Dieting works, but without it, it only makes things worse”, he says.

Marketing employee Helen Bermudes, 28, started less time ago. She started intermittent fasting three weeks ago and found out about the restriction about 30 days ago via TikTok and Instagram. “I started following a girl who is also going through the postpartum process. I want to enhance my weight loss process, I do food reeducation, abdominal hypopressive and finally fasting. I started with 14 hours and now I have increased the duration (16 hours)” , she says.

Influence of social networks

Doctor Fernando Gerchman says that although intermittent fasting is a viable option to lose weight, many people end up starting the practice when they are influenced on social networks, which can bring health risks. “There’s a lot of misinformation out there about intermittent fasting, it’s something we’re trying to combat. Before any diet, you have to do a clinical evaluation. Based on that, we’ll have an idea if there are any contraindications or not”, he emphasizes. He exemplifies that people with more fragile health and balance problems, for example, may end up not adhering to fasting.

For nutritionist Cintia Squeff, the contact of people on social networks and the beginning of intermittent fasting soon after seeing the publications have to do with the population thinking that weight loss is something quick and without much complexity. “People are used to this immediacy. And they forget that weight loss is not just about food. It is about 80% of food, but there are also factors such as mental health and the functioning of organs such as the intestine, for example, which greatly influence the process” , emphasizes.

The employee in the Marketing area, Helen Bermudes, follows up with a nutritionist from the Unified Health System (SUS), who recommends more affordable foods that can be consumed in the food window. In addition, it has two apps to assist in practice. One of them points to a kind of “fasting clock”, where the amount of time without eating and when the next cycle of food restriction should start is displayed. Kethlin Cruz does not follow up with health professionals, but also records food fasting in an app. “It was independent (the fasting process), but I try to consume the content of some nutritionists,” she says.



Many people know about intermittent fasting through social media | Photo: Ricardo Giusti

Study in China says fasting is no more effective than other dietary restrictions

One study in china year, published by The New England Journal of Medicine last week, with 71 men and 68 women, concluded that the measure is not more affective than purely caloric restrictions to lose weight. As a methodology, the scientists made caloric restrictions and followed the diet of two groups. The difference is that one of them had only 8 hours (from 8 am to 4 pm) to eat and the other had no time restriction for eating.

The consumption of calories (0% to 55% of carbohydrates, 15 to 20% of proteins and 20 to 30% of fat) of the two groups was 1,500 to 1,800 kcal in the male group and 1,200 to 1,500 in females, and participants were encouraged to weigh foods to certify consumption in the correct proportions.

Individuals were also required to record their daily food consumption and take pictures of the food, in addition to detailing the follow-up in a specific application for the study. In the end, the group that didn’t do intermittent fasting lost an average of 6.3 pounds, and the people who did lost 8 pounds. According to the researchers, the result is not enough to declare intermittent fasting a more successful way to lose weight.

Fasting according to routine and physical conditions

Doctor Fernando Gerchman believes that the central issue should not be the effectiveness of intermittent fasting in relation to other regimens. The biggest discussion, according to him, is that the measure together with a healthy diet brings satisfactory results for weight loss. “We are trying to find out which is the best profile to indicate intermittent fasting. There are already studies in different populations, in a population with type 2 diabetes mellitus. And the results are that they (fasts) are effective in causing weight loss and even eventually do glycemic control”, he declares.

Marketing professional Helen Bermudes managed to adapt the fasting starting more at night. In this way, she is able to stop eating at a not-so-early time and eat the next day around noon. “It’s been super quiet, because I do it at night. My last meal ends up being around 8pm,” she says.

For her, fasting helped her feel less hungry, without needing to eat large amounts of food to be satisfied after a meal. “It’s helping a lot. I even feel that I get more satiated when I eat,” she says. Production Engineering student Kethlin Cruz also highlights the same benefit. “The most important difference for me was the amount of food I ate before to how much I can eat now. It’s exorbitant,” she points out.

Caution needed, warn nutritionists

Nutritionist Cintia Squeff understands that the subject should be treated with caution and warns that, if the person really wants to start the practice, they should start the period of food restriction at night. For example, from 7pm to 7am the next day. “It can bring benefits, control blood glucose, reduce body fat, in addition to reducing blood pressure,” she says. “Fasting may not be good for diabetics, pregnant and lactating women,” she points out.

Squeff mentions that a big problem is the fact that people don’t take care of their food during the food window period. “There are patients who go 16, 24 hours without eating and eat a cheese, then feel sick. In consultations, I prefer to cut patients’ food at an earlier time, but not do this fast”, he argues.

Criticism of studies

The assistant nutritionist at the Santa Casa de Porto Alegre Obesity Treatment Center, Jéssica Polet, criticizes the studies carried out on intermittent fasting. According to her, there is a lack of research that presents the long-term effects of the practice and the target audience of the analyzes is usually young and middle-aged adults with overweight, and there is no clarity on the possible benefits for individuals of other age groups. She also doesn’t usually recommend intermittent fasting. “I believe it is a strategy that can be adopted in some specific cases and in the short term, as a ‘start’ of dietary changes, but not a dietary pattern to be encouraged for all people”, she highlights.

Regarding the possibility of elderly people doing the regimen, Fernando Gerchman says that every case must be analyzed. “I increasingly think that age shouldn’t be an impediment to anything. We have 80-year-olds today in full physical health. Evidently, older populations will have a lower tolerance for diets that are more life-modifying. They have a fixed food habit for a long time”, he explains.

long term fasting

Both Kethlin Cruz and Helen Bermudes say that intermittent fasting should not be something momentary in their lives, but a practice that they should continue with them for a long time to come. “I like to fast. Most of the time I feel good when I do. So maybe yes, I’ll keep doing it for a long time,” says Kethlin. “I feel like it can be long-term. I see it being beneficial,” says Helen.

Nutritionist Jessica Polet does not believe that intermittent fasting should be done for a long time, as she considers that it can cause various harm to people’s health. “Fasting for long periods and too often can lead to nutritional deficiencies, dehydration, fainting and worsen eating disorders such as binge eating,” she points out.


Fernando Gerchman says that research on intermittent fasting is still not advanced and in the future it may be clearer who has all the recommendations to make. “We are still a long way from, based on physical and genetic characteristics, putting the matter on the computer and recommending this type of diet through artificial intelligence. We will get there as the years go by”, he projects.

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