LET’S TALK ABOUT INTERMITTENT FASTING

The question in vogue is none other than intermittent fasting, a very widespread practice these days among those who wish to lose weight. Fasting is nothing more than not eating food for a period of time, but how long, for what purpose and under what conditions it is or is not advisable are the real questions of interest.

Let’s start by understanding how our body works after eating. When we finish eating, energy is distributed throughout the body, and when we eat more food than we need, the body stores the excess in the form of fat. 

About six hours after the last meal, the body consumes the energy stored in the liver. After 12 hours of fasting, the insulin level is reduced, and the body begins to convert the calories into glycogen for delivery to the liver and muscle stores. Then, once the glycogen is depleted, the body turns to fat stores to continue supplying nutrients to the body in the absence of new food intake.

Intermittent fasting is not a diet, it is a dietary model that goes in cycles, with periods of fasting and intakes, where the times and schedules of meals set the pattern. The most important thing to point out about this model is that it should never be started without a prior study by a health specialist, trained to assess the physical and energetic condition of the person, as well as to guide and monitor this process, which should not be excessively prolonged, as not everyone needs it or can do it.

Fasting has certain advantages for health when it is well directed, but it can also cause some damage if it is extended in hours and is done without control. It is something that we already do naturally with overnight fasting, which usually lasts about 8 hours, and during this time some benefits develop, for example, the regulation of circadian rhythms and sleep quality. 

The most consistent fasting is one that is in line with the body’s biological rhythms and circadian cycles, one that begins at dusk and breaks at dawn, when the digestive juices are ready for their ideally cooked, alkaline and gentle nourishment.

In Spain, we have the habit of having a late dinner and eating large quantities of food, which causes a feeling of blockage of systems and lack of appetite, a situation that “forces” us to wait until mid-morning to start eating food with a certain appetite. In fact, most of the time, the fast is broken with coffee or food that is extremely acidic for the body.

This kind of fasting imposed by the previous night’s excess is a fast that is distorted by working both the digestive and nervous systems all night long, instead of letting both benefit from the nightly repair cycle. Therefore, it is as important to know how to break fasts properly as it is to know how to choose what to eat at mealtimes. And I insist that this should be a totally personalised guideline for the person who is starting this process.

Intermittent fasting can be done in different ways, the most popular being the 16:8 mode, which consists of fasting for 16 hours at a time and devoting the main 8 hours of the day to eating. Other popular forms are: 

Fasting for 12 hours a day. Include sleep time in the fasting window and try to consume the same amount of calories each day. For example, you eat dinner at 9 pm at the latest and do not eat again until 9 am. The main benefits of 12-hour intermittent fasting are to contribute to the cellular repair process, gain mental health and clarity, reduce insulin resistance and, for many women, help with weight loss.

Fasting for 2 days per week. This consists of eating regular amounts of healthy foods for 5 days and reducing your calorie intake on the other 2 days.

Alternate-day fasting or 5:2 diet. Some people avoid eating solid food on fasting days or consume up to 500 calories, and on non-fasting days eat as much as they feel like eating. This extreme form of intermittent fasting is not suitable for people with certain medical conditions.

However, during feeding times it is not enough to eat whatever we feel like eating. Dishes should contain nourishing foods, vegetables, quality vegetable and/or animal protein sources, omega 3 from plant sources or oily fish, whole grains and fruit, and avoid processed foods, sugars or white flour. Along with good hydration. 

It is true that when food is not introduced for a while, the digestive system rests, which helps to improve the function of the intestinal barrier, with an increase in the production of Lysozyme, a molecule that prevents the proliferation and growth of bacteria. It is even said that fasting may boost autophagy, the natural mechanism of cell regeneration that prevents the accumulation of waste products, regulate cholesterol, improve insulin levels, reduce markers of oxidative stress and lose weight.

But some harm can also be done when it is not done in a controlled way.

If fasting is carried out for too long and without taking into account possible pathologies, fainting, general fatigue, dehydration, stomach disorders or sudden episodes of decreased blood pressure may occur. In the case of people aiming to increase their athletic performance, they can deplete their energy reserves, reduce their aerobic capacity and lose muscle mass.

An article published in 2019 in the prestigious journal The New England Journal of Medicine, looked at the potential difficulties that can arise from carrying out this strategy in real life. Firstly, the current diet of at least 3 meals a day, along with snacks between meals is very established, making it difficult to change this habit in the general population. Secondly, during a period of fasting, hunger, irritability and reduced ability to concentrate can be experienced, and these adverse effects can lead to rejection.

Therefore, once again, common sense prevails. Listen to your body, align it with the rhythms of nature, analyse your personal goals and ask a health professional for guidance on the best plan to achieve them. What is clear to everyone is that after fasting for a few hours, the stomach likes what you like, to be reactivated slowly, gently, with foods that are easy to digest, alkaline, hydrating, nourishing and comforting.

María Kindelán