Maintaining body weight within the normal range provides many advantages. People without excess weight are less susceptible to the appearance of joint pain, the development of diabetes mellitus, cardiac and some oncological diseases. You can maintain a healthy weight using different methods. For several decades, the Mediterranean diet has been considered one of the most useful nutrition systems, which allows not only to maintain normal weight, but also is the source of most of the essential nutrients for the body.
However, in recent years, another fashionable diet has appeared, which many consider a panacea for obesity and the easiest way to lose weight without giving up your favorite foods. We are talking about interval fasting. Is this system as useful as many people are sure what it is and are there contraindications to interval fasting? Let’s figure it out together, based not just on the enthusiastic reviews of those who lost weight, but on real scientific facts.
What is interval fasting?
Interval fasting, or fasting, is a regime in which it is necessary to completely abandon eating during certain time frames, and the rest of the time to eat as usual.
Intermittent fasting is a fairly flexible system. Everyone can determine for himself the duration of the period for which he plans to give up food.
There are different models of IF:
In addition, many people follow the 5:2 system – when the daily calorie intake is reduced to 500 kcal for 2 days a week, and on the rest of the days they adhere to the traditional diet for themselves.
But still, when they talk about interval fasting, they most often mean the 16 system:8. It provides for daily fasting for 16 hours. An 8-hour window is allocated for eating during the day. At the same time, there are no strict restrictions on when it should be. Some people feel comfortable skipping breakfast in favor of a hearty lunch and dinner, others, on the contrary, refuse an evening meal. And it does not affect the result of the IF. The most important thing is to eat only during the 8-hour window.
For comparison. In the 20:4 system, only 4 hours are allotted for meals per day. Such a system allows you to lose weight more quickly, but as a long-term nutrition model, this is not the best choice.
In fact, each period of time between meals can be called interval fasting. For example, when a person does not have time to have breakfast in the morning and the first meal after dinner falls on lunch, this is already interval fasting. But if the task is to get real results from the IF, then such a system should become regular.
How it works
The essence of IF, regardless of the chosen model, is identical: during the period of a sharp decrease in calories, the body uses accumulated fat to obtain energy.
IF is not something new. This is one of the oldest food systems. This is exactly the way of life that ancient man led.
From the point of view of food consumption, the human body can only be in one of two states: satiety or hunger. That is, either the body accumulates energy from food (increases its energy reserves), or burns stored energy (reduces reserves). If the periods of nutrition and hunger are balanced, then the body weight does not change significantly.
Modern man, as a rule, consumes more food than the body actually needs. Everything that has not been used is deposited in the “storerooms” in the form of fat accumulations. That is, if a person, starting in the morning and until late in the evening, eats food, then the body is constantly in a full state and accumulates energy. So over time, excess weight and obesity appear. Interval fasting helps to restore this balance. Simply put, IF allows the body to expend stored energy.
When we eat, the body uses carbohydrates as energy, and the excess deposits in the liver in the form of glycogen or turns into fat. After the meal, the body uses the carbohydrates obtained as “fuel” for several more hours. The accumulated “fuel” in the liver-glycogen is enough for about 8 more hours, and if after this time the body is not given another portion of food, it begins to take energy from the accumulated fat.
Thus, the longer the fasting period, the more fat the body will consume. But as soon as he receives the slightest portion of carbohydrates, for example, in the form of coffee with a minuscule amount of sugar, the process of splitting fats will stop and the body will switch back to the mode of burning carbohydrates and accumulating glycogen, as well as fat.
That is, if the last meal was at 22:00, then the body will start burning fat at about 6 o’clock in the morning. If breakfast is at 8:00, then there is only 2 hours left to burn fat reserves. And fasting allows you to extend this time.
What modern research says
The first studies on the topic of interval fasting and its effect on the human body were conducted back in 2012.
Then a group of American researchers, after prolonged observations, came to the conclusion that IF brings more benefits to the body than the usual calorie reduction. The scientists conducted their first studies on mice. Two genetically identical groups of mice took part in the scientific experiment, which were fed food with a high content of fats, simple sugars, and also with a low content of proteins (about the way most modern people eat). Despite the fact that both groups of animals consumed the same food, the former had access to it for 24 hours, while the others had only 8. After 18 weeks, mice that could eat at any time showed signs of insulin resistance, as well as liver damage. Representatives from the other group did not have such signs, despite the fact that everyone had the same calorie intake. Later, the scientists repeated the same experiment with 3 more groups of mice and got the same result each time.
During the study, experts found another interesting point. The shorter the window of food intake, the less weight the animals gained. But even when the mice were given two days off a week and could eat without restrictions, the animals still gained less weight than their “brothers” who had access to food for 24 hours a day.
Then the same scientists conducted another experiment. They transferred mice that gained excess weight due to unlimited nutrition to interval fasting, while the daily caloric content of the diet was not changed. The animals got rid not only of excess weight, but also of insulin resistance.
Of course, more complex processes occur in the human body than in the bodies of mice, but interval fasting affects a person in about the same way.
Advantages of interval fasting
Based on the results of scientific research, many scientists claim that IF has a positive effect on the human body. Among the most obvious advantages is the loss of excess weight, but this is by no means the only plus of such a power system. Various popular systems of detoxification and purification of the body from toxins and toxins are built on the principles of fasting, which in turn is called one of the factors that slow down the aging process.
According to research, compliance with IF contributes to:
- faster breakdown of fat, including visceral;
- reducing blood sugar levels and the amount of insulin produced;
- reducing the risk of developing type 2 diabetes;
- improving brain function and concentration;
- reduction of cholesterol in the blood, including “bad”;
- the process of autophagy (cleansing of dead cells);
- the production of growth hormone (in combination with autophagy promotes the renewal of the body);
- reducing the risk of inflammatory processes;
- normalization of the body’s sensitivity to leptin (the hormone responsible for hunger);
- improvement of intestinal motility.
In addition, many people who follow the IF system claim that they feel more cheerful, react more easily to stressful situations and concentrate more easily on work.
Contraindications to IF
Despite the impressive list of positive properties, fasting in some cases may be contraindicated. In particular, the ban applies to people who need a diet rich in nutrients, and this:
- pregnant and lactating women;
- persons with insufficient body weight (BMI below 18.5);
- people with eating disorders, for example, anorexia.
It is also worth considering that in some cases, side symptoms occur against the background of IF, for example:
- a strong feeling of hunger (as a rule, if there are too few carbohydrates in the diet); constipation;
- headaches (usually in the first days of IF);
- dizziness (usually if you consume very few calories during the food window).
To avoid side effects, do not start immediately with a small food window. If you are used to eating from the very morning until late at night, you can first reduce the food window to 12 hours, and then gradually bring it up to 8, 6 or even 4 hours a day.
Interval fasting is a very flexible system and everyone can choose the most comfortable model for themselves. But still, if the main goal is to get rid of excess weight, then even during the food window it is worth taking a more careful approach to the choice of products, giving preference to useful ones. In addition, no matter how healthy IF is considered, observing this nutrition system, it is necessary to listen to your body and not overdo it, because prolonged refusal of food can be no less dangerous than regular overeating.