Intermittent fasting or cessation of food consumption for a few controlled hours has become a form of eating with multiple benefits.
If we look up the term “fasting” in the dictionary, the first thing that will be described is total or partial abstention from food and / or drink, in some cases for religious reasons. However, within this broad term, intermittent fasting has been gaining prominence in recent years as one more way of eating, always accompanied by a good food base.
Historically, there was an involuntary fast at the time of the hunter man: if there was food, they could eat, and if not, they had to fast; It was easy, but not controlled, and in these cases the fast could last from hours to several days. Currently the most notable voluntary fasting is religious, but intermittent fasting is gaining followers for its potential benefits on human health.
Today we will explain what exactly intermittent fasting is, what benefits it brings and how we can practice it in a controlled way.
What is intermittent fasting
Intermittent fasting, as its name suggests, is not a total and uncontrolled fast but voluntary and well thought out. Although this type of fast can provide certain benefits after the first 12 hours without consuming food, the best thing to do is too fast for a minimum of 16 hours and even up to 24 or 36 hours as we will explain later.
Although previously many individuals believed that intermittent fasting causes a series of damages in the human body, especially in terms of sports performance, these are myths that have been banished one by one in recent years.
Myths and potential benefits of intermittent fasting
For example, that intermittent fasting can cause a slowdown in metabolism, or even that such fasting can cause loss of muscle mass. Both myths fall apart under their own weight, since this type of fasting was practiced involuntarily in Paleolithic times when humans went hunting. If either of these two situations really occurred, the hunters would not have been able to endure hours and much less days searching for food as they used to do.
As if this logic were not enough, scientific studies also contradict myths. On the one hand, a work published this year in the Annals of Thoracic Medicine states that intermittent fasting increases the production of orexin, a neurotransmitter that would increase metabolism (not reduce it as is often thought). On the other hand, it should be noted that a total fast of three days would slow down the metabolism, although only 8% according to a study published in 1987 in the American Journal of Clinical Nutrition.
On the other hand, as far as muscle is concerned, research has also reached conclusions totally contrary to the most widespread myths: intermittent fasting can reduce muscle loss, and increase fat loss, according to a published 2011 work in Obesity Reviews.
Finally, a couple more myths about intermittent fasting should be highlighted: that it can increase the risk of hypoglycemia or low blood sugar, or that it can even cause weight gain (as a possible rebound effect after spending too many hours without consuming food). The reality is that intermittent fasting has been shown to improve insulin sensitivity, even in individuals with type 2 diabetes mellitus. An exception would be individuals prone to hypoglycemia or low blood sugar, in which there is still a lack of evidence. It is also worth noting that intermittent fasting while taking diabetes mellitus drugs, such as insulin, should be more strictly regulated to avoid unnecessary risks.
Finally, regarding weight gain, it is a myth with little logic. When you eat again after fasting there is no increase in hunger, and in fact intermittent fasting has been shown on several occasions to be a good method to lose weight, as stated in a 2015 work published in the International Journal of Obesity.
What types of intermittent fasting are there?
There are multiple ways to practice intermittent fasting, although today we will only name the most commonly practiced ways.
12 hours fast
The easiest way to practice intermittent fasting, and one that many of us already do without realizing it, is the 12-hour fast: just sleep the recommended eight hours a night, having dinner relatively early (around 8:00 or 8:30 p.m.) and have breakfast the next day around 8:00 or 8:30 in the morning. In this case, it would be a matter of opening the typical fasting window a bit, just having dinner a little earlier or having breakfast a little later. As I say, many individuals already perform this "fast" on a daily basis without being aware of it.
16 hours fast
Although this initial fast would already provide some other health benefits, it would be necessary to go a step further in intermittent fasting with the 16-hour fast or the 16/8 fast. Although there are also several ways to do it, the easiest would be similar to the previous case: having dinner around 8:00 or 9:00 p.m. and not having food until lunch at 12:00 or 13:00 the next day. Other methods would be to eliminate dinner and advance breakfast time a bit (eat around 3:00 p.m. and have breakfast the next day at 7:00 a.m. for example), or have a snack at 6:00 p.m. the afternoon and not eat anything until breakfast a little later than usual, around 10:00 h.
On a personal level, the only method that I have tried myself a couple of times is this type of 16-hour fast, usually after a larger than usual dinner (on the weekend). In times of hunger, it is usually advisable to drink water, herbal teas or even coffee without sugar, milk or any other companion (and it usually works quite well).
On the other hand, another step in intermittent fasting would be the 24-hour fast also known as Eat Stop Eat, a type of fast that is not recommended to be performed more than once or twice a week, and on non-consecutive days. In this case there are two ways to do it, for example having dinner around 8:00 pm and not eating again until dinner the next day; or having breakfast around 8:00 in the morning and not having food until the same time the next day.
Finally, there is fasting on alternate days, fasting 5: 2 or alternative day fasting. This type of fast is a little different from the previous ones, since it involves two days of calorie consumption limited to 500-600 kcal per day, twice a week, alternated with five days of consumption without any type of restriction. This form of fasting is the most popular in Anglo-Saxon countries, and shares some characteristics with Eat Stop Eat, such as the fact that it cannot be performed more than twice a week, and always alternating with days of normal food consumption.