What is intermittent fasting?

Intermittent fasting (better known as intermittent fasting or IF in English) is a general term that describes a period in which regular fasting and feeding cycles are performed. Intermittent fasting is not a diet in itself, although it can be used in conjunction with a calorie restriction for weight loss. (1)

We find different types of intermittent fasts. The first and best known is the 16/8 (16 hours of fasting / 8 hours being able to eat). The first thing that can come to mind is that you will not be able to get it since you think it is difficult to be 16 hours without eating, but this is not so, since only counting the time we spent sleeping this goes from 8- 10 hours normally, all you should do is delay your first meal several hours, and it would be achieved. 

It has been shown that this type of fasting has many advantages such as those mentioned below – 

A group of American academics, from the University of Illinois, from Indiana and the Salk Institute for Biological Studies, made a small 12-week intervention with 23 patients obese to study the effect of the 16: 8 diet.

The results, published in the scientific journal on nutrition and ageing Nutrition and Healthy Aging, showed an average weight loss of 3kg in 12 weeks, and also an average daily reduction in the number of calories ingested from 341cal. (2) 

But not everything was going to be good, and it also has some disadvantages such as the following: – 

Increase in fat: intermittent fasting may lose weight temporarily, but it is NOT the best method. The initial loss of fat when we are in a state of alertness (sympathetic) can degenerate in the opposite once we have adrenal fatigue and cortisol and insulin begin to have irregular patterns. It is the “yo-yo” effect of constant weight losses and gains. The determining factor here is your adrenal resistance.

– Hormonal and circadian deregulation: the priority of our body is to survive, and when the mechanisms of stress are activated, everything else is secondary. In this context, pregnenolone levels (precursor of sex hormones) decrease in favour of cortisol. From there it is only a matter of time that problems of infertility, impotence, muscle loss, chronic fatigue develop … etc. Women are even more susceptible because they are not “natural hunters” and, therefore, are not as well adapted to fasting as men (3)

Other types of intermittent fasting are the following: 

Intermediate: 20/4

In this case, we increase the fasting period until 20 hours, leaving only four hours a day in which we can eat. In the end, the usual thing with this fasting structure is to make a meal or, at most, two. 

Diets like The Warrior Diet are based on this structure and promise to be able to achieve results without controlling too much what we eat. In the end, with just one meal a day, it is quite difficult to spend. 

Contrary to what one might think, a recommendation by the author of the method is to leave the feeding period (four hours) by the end of the day. Make a more forceful dinner than usual and the rest of the day we can drink water, coffee alone or tea.

Fasting on alternate days

Even if it is the most extended fast on the list, do not think that it is something “extreme” and no, you will not go hungry. In this study, the appetite was analyzed during 24 hours of fasting and, contrary to what it may seem, the individuals did not go hungrier than average. 

As we see in the study, ghrelin, the appetite hormone, goes up and down throughout the day depending on our habits and has little or nothing to do with the hours you have been without eating. Therefore, even if you don’t believe it, it is easy fast to carry. The first day will be the hardest, and it will be easier for you to endure.

Besides, other studies have analyzed how our metabolism reacts during a fasting period, and this, not only does not go down but goes up. The reason for this is that during fasting, your body secretes hormones such as adrenaline or growth hormone and this keeps your body “accelerated” during the day. 

One of the diets that have applied this fasting structure is the Eat Stop Eat which consists of fasting for 24 hours during alternate days and, as we see in the studies, it works. In the study, the groups that were intermittent fasting managed to lose fat after eight weeks without losing any muscle mass. 

(1)  https://es.wikipedia.org/wiki/Ayuno_intermite

(2)  https://www.bbc.com/mundo/noticias-44601578

(3)  https://www.saludestrategica.com/2-peligros -fast-intermittent-fasting /

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