The good, the ugly, and the bad about intermittent fasting


The good, the ugly, and the bad about intermittent fasting


It is not a diet but a strategy that consists of performing a period of fasting in a certain time and then eating food in a set range of time

The good, the ugly, and the bad about intermittent fasting

In the consultation of dietitians-nutritionists there is a concept that has gained such prominence in the last two years that at times it overshadows the word “diet”. And this concept is the intermittent fasting. It is not a diet as such but rather a dietary strategy that consists of performing a period of fasting in a certain time (there are different modalities) to later eat food in an established time range, according to Elisa Escorihuela, dietician-nutritionist, pharmacist and author of the ABC Bienestar blog «Nutrition Classroom».

Google searches to find out “what is intermittent fasting”, “what are the benefits of intermittent fasting” and “how to practice intermittent fasting” have multiplied in the last ten years, although it has been in the last three years when an exponential increase has been noticed, in the heat of the famous ones who have declared to follow this dietary strategy as is the case of Kourtney Kardashian, Nicole Kidman, Hugh Jackman, Benedict Cumberbatch, Jennifer Aniston o Elsa Pataky. Precisely the latter is the one that motivated the last search spike in Spain that coincides with the day, she explained during her participation in the television program “El Hormiguero” that both she and her husband, Chris Hemsworth they practice a daily fast of 16 hours, that is, what is known as an intermittent fast 16/8, which involves 16 hours of fasting and dosing the food intakes in the remaining 8 hours. One possibility to carry out this formula, according to the nutritionist Nazaret Pereira, founder of Nutrition Pereira, could be to have breakfast and eat and then not eat again until the next day.

Types of intermittent fasting

But there are other ways of practicing intermittent fasting. The simplest is called 12 / 12, which consists of fasting for 12 hours and that could continue to advance dinner time (at eight in the afternoon) and delay, if breakfast is usually eaten earlier, the time of breakfast (at eight in the morning).

Another stricter pattern, as described by Nazaret Pereira, is the intermittent fasting 20/4, in which they eat a daily meal (following the formula “one meal a day”) or two meals spread over a maximum period of 4 hours and the rest of the time they would remain fasting.

The fast of 24 hours, the fasting on alternate days and the formula named PM5:2. The first consists, as the expert Elisa Escorihuela specifies, in spending a total of 24 hours without consuming food and that can be done, for example, if on Monday you eat at 13:5 p.m. and you do not eat again until Tuesday at the same time. hour. And fasting on alternate days would be designed to be carried out for a week and would consist of fasting every other day. The 2: 300 fast would be another weekly fasting modality and would consist of eating five days regularly and two of them reducing the energy intake to about 500-25 kcal, XNUMX% of the requirements that the body usually needs.

The types described would be the most popular, but there are other intermittent fasting modalities that, like the previous ones, should have, according to experts, the monitoring and control by a dietitian-nutritionist.

What are the benefits of intermittent fasting?

Scientists have been studying intermittent fasting for a couple of decades, but some of the mechanisms behind this dietary strategy are not well understood. A recent review of studies on this subject published by “The New England Journal of Medicine” and signed by neuroscientist Mark Mattson concludes that the key to the benefits of this formula would be in a process called metabolic change and that it is precisely the fact of frequently exchanging metabolic states that produces the healthy benefits of intermittent fasting.

These benefits, as explained in said analysis, would have to do with a improvement in blood pressure, in the resting heart rate, in the fat mass reduction obesity prevention and the reduction of tissue damages.

What this review suggests is that time-restricted feeding methods could provide health benefits without reaching 24 hours of total fasting, with the 16/8 formula being the easiest to implement. Not surprisingly, another recent study published in “Science” finds that a 14-hour fast could already bring health benefits.

Also, another recent review of papers and articles on temporary and intermittent caloric restriction called “Effects of time-restricted feeding on body weight and metabolism. A systematic review and meta-analysis »revealed that intermittent fasting helps reduce risk factors for diseases such as metabolic syndrome, cardiovascular and neurodegenerative diseases, or even cancer.

Other benefits listed in this other review are the improved insulin sensitivity, regulating blood pressure, reducing body fat and increasing muscle mass. Although it is important to clarify that the conclusions of this review also contain a recommendation from the scientists who see the need to continue investigating the mechanisms that are activated during the practice of intermittent fasting to confirm the solidity in the medium and long term of these benefits.

More research is needed

The conclusions of these investigations, however, contrast with those of the Nutrimedia project, of the Observatory of Scientific Communication of the Department of Communication of Pompeu Fabra University, which carried out a scientific evaluation of the veracity of the use of intermittent fasting to reduce or improve weight. health.

This study concluded that, after analyzing the evidence available today, the practice of sporadic or intermittent fasting for health reasons has no scientific justification. In addition, in their report they remember that the Association of Dietitians of the United Kingdom and the American Institute for Cancer Research coincide in recognizing that, although there have been potential health benefits with fasting, this practice can cause adverse effects What irritability, difficulty concentrating, sleep disturbances, dehydration, and nutritional deficiencies, and potential long-term health consequences are unknown.

Nutritional advice, essential

What the experts do agree on is that fasting cannot and should not be an excuse to eat poorly or in an unhealthy way, that is, if it is carried out it must be carried out under professional supervision and is not Recommended for those who have suffered or are suffering from eating disorders or eating disorders, neither for children, the elderly or pregnant women.

The key is that this practice, once controlled and advised, is integrated into a balanced and varied diet, rich in fruits, vegetables, whole grains, legumes, nuts and proteins and in which ultra-processed foods, high in sugars and saturated fats.

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