Intermittent fasting: does it help to lose weight and how to start

Interval fastingis one of the most popular ways to lose weight in recent years.It has confidently surpassed the famous Dukan diet, ketodiet and the slightly lesser known, but no less effective Weight Watchers (WW) diet.And although the name of the method may not be very encouraging, and some may even be frightened - many people are happy to lose weight with the help of interval fasting and do not even feel any discomfort.

This diet is also called “interval dieting” (sounds more pleasant), “periodic or cyclic fasting”, and in English-language literature - “intermittent fasting” or “fast diet”.

It is believed that its roots go back to antiquity: the prototype of intermittent fasting for Christians is Lent, for Jews - Yom Kippur, and for Muslims - Ramadan. In the Middle Ages many diseases were also treated with the help of fasting. Firstly, then doctors really believed in its miraculous power, and secondly, such treatment was definitely affordable for everyone. And Indian yogis refused food for a long time, thus “cleansing” the soul and body.

What is interval nutrition?

As the name suggests, interval eating is the alternation of periods of eating and hunger. The time when you can eat without worrying about your weight is called the “food window”.

Where did the idea of interval fasting come from in the first place? It is believed that this diet was developed by bodybuilders' trainers, because it not only helps to get rid of fat deposits, but also preserves (and for many people improves) the relief of muscles. Unlike traditional “drying”, interval nutrition is not so harmful to the body - moreover, according to studies it is even beneficial for metabolism and cardiovascular health.

Fast dieting is often associated with autophagy. This is a process in which cells “eat” their own components. It was described in detail in 1990 by Japanese scientist Yoshinori Osumi in a study of yeast fungi. Subsequently, it was suggested that a similar process occurs in the human body under conditions of starvation, and it is this process that promotes rejuvenation, health and “enlightened” thinking activity.

To understand how interval fasting works, you need to have a good idea of where the body gets energy for life activity. So, in normal life, energy is provided by glucose, into which food is converted after it has been broken down and through a number of biochemical processes. Part of glucose is stored in the liver and muscles in the form of “energy reserve” - glycogen; in addition, our body does not forget about NZ (inviolable reserve) of nutrients - adipose tissue.

If the body does not receive food for a certain period of time, it begins to use up glycogen. But after 12-24 hours its reserves are depleted, and the body has to switch to an alternative source of nutrition - its own fat reserve. This condition is called ketosis, and it is this condition that promotes weight loss.

Compared to other diets, intermittent fasting has a number of advantages:

• it does not require meticulous calorie counting;
• there is no need to carefully consider the menu and search for quinoa, red fish and other expensive products in stores;
• no need to spend a lot of time on “cooking”;
• conditionally you can “eat whatever you want” (of course, with reasonable restrictions).

Another difference of interval fasting is the benefit for the body, which has been confirmed in relevant studies. This diet is advised not only by girlfriends and bloggers, but also by nutritionists and doctors, especially endocrinologists. Interval fasting is widely used for weight loss, especially in metabolic disorders (such as reduced sensitivity to carbohydrates).

Types of interval fasting

Traditionally, the following types of interval fasting are distinguished:

• methods 14/10, 16/8, 18/6, 20/4 (19/5);
• 5/2 method.

In the first case we are talking abouttime-restricted feeding during the day (time-restricted feeding, or TRF) - for example, according to the scheme 16/8 a person fasts for 16 hours, but can eat only for 8 hours - from 10 am to 6 pm.

Interval fasting 5/2 - this is eating according to the principle “everything is allowed” 5 days a week and fasting for 2 days. But in fact, this scheme does not require a complete refusal of food, and in the “hungry” days you can eat 500-600 kcal per day.

The most popular scheme of interval fasting is 16/8. It is quite close to the standard dietary regimen and usually does not cause a person much discomfort.

The author of this scheme is Martin Berkhan. He received a medical degree, and then worked as a fitness trainer, so his diet is aimed not only at weight loss and general recovery, but also at creating body relief.

According to the 16/8 scheme, you can have breakfast at 10, and dinner at 18 hours or at 12 and 20 hours, respectively. It is better to choose the optimal mode taking into account your biorhythms: for example, a “lark” will find it very difficult to go without food until noon, while an “owl” will just wake up by this time.

The 5/2 method is ideal for people who do not want to monitor the “correctness” of nutrition every day - it is much easier for them to limit themselves in calories within 48 hours. Also this scheme is indispensable when a person works or studies - he chooses convenient “hungry” days for himself.

Other interval fasting regimens:

• 14/10 (13/11) - the “mildest” version with a 10-11 hour food window;
• 18/6 - involves an 18-hour food pause (e.g., from 6 p.m. to 12 a.m.);
• 20/4 (military diet) - starvation for 20 hours and one meal with a snack, usually in the evening;
• the eat-stop-eat method - complete abstinence from food for 24 hours (1 or 2 times a week).

Is interval fasting helpful?

“Does interval fasting help” is one of the most common questions on the internet. Given the popularity of this diet, its effectiveness and impact on the body's health have been repeatedly evaluated in various studies. The results of interval fasting have been published in relevant articles on the National Library of Medicine (PubMed) website:

• “Interval fasting and metabolic health” ;
• “Intermittent fasting methods for the treatment of overweight and obesity in adults: a systematic review and meta-analysis” ;
• “Intermittent fasting as a nutritional method against obesity and metabolic diseases” ;
• "Interval fasting: a heart-healthy diet? ” and others.

Studies confirm that interval nutrition is indeed effective for weight loss. Moreover, it also has a positive effect on the body's metabolism - for example, it can reduce insulin resistance and improve the lipid profile (the ratio of healthy to harmful cholesterol in the blood). This diet also has some anti-inflammatory activity, which may prove useful in the treatment of cardiovascular disease or non-alcoholic fatty liver disease.

“Amounts” of weight lost vary from person to person and depend on initial weight, comorbidities (e.g., metabolic syndrome, diabetes), the fast diet regimen chosen, and physical activity. According to the results of various studies, weight loss averaged 0.8-13% - this is considered a pretty good indicator, given that in most cases, observations of thinning people were not very long.

What and how to eat during interval fasting?

Proper nutrition during interval fasting is very important. If it is unbalanced - the body will begin to suffer from a lack of useful substances, vitamins and minerals.

In order not to experience discomfort from a constant feeling of hunger, you should lean on protein - beans, lentils, soy, chicken and turkey meat. Also in the diet must necessarily be present vegetables and fruits - it is not only a source of vitamins, minerals, antioxidants and fiber, but also “bulk mass” that fills the stomach and creates a sense of satiety.

Easily digestible carbohydrates (cakes, pastries, sweet carbonated drinks) are best avoided if possible - they provoke the development of insulin resistance and do not contain special “usefulness”. But this does not mean that they should be completely abandoned. As a rule, all easily digestible carbohydrate food is tasty - which means that it can be used as an antidepressant when a proper and healthy diet becomes too sad. The same is true for sugar and trans fats.

With the 16/8 pattern, there can be 2 or 3 full meals. For example, at 12 o'clock you can have a breakfast of omelet with vegetables and whole-grain toast with avocado, at 15 - lunch of chicken fillet and buckwheat with salad, and at 19 - dinner of baked fish with stewed vegetables. Not the most horrible eating regimen, right?

With the military diet, the food window is only 4 hours, so nutritionists recommend moving it to dinner. For example, from 6 to 10 pm you can eat chicken with a side dish and salad, and snack on fruit, nuts and yogurt.

It is also important not to forget the following:

• interval eating will only help you lose weight if you stick to it regularly. “Starving” correctly 3 days a week, and eating without any intervals 4 days, the body will start to store fat and weight will creep up;
• regardless of the interval - you need to drink enough. It is better that it was water, but tea and coffee without sugar, non-caloric drinks (for example, diluted juices) are also allowed;
• when choosing a portion, focus on your own feelings, not on the upcoming “hunger” period. There is no need to overeat in the hope that it will prolong the feeling of satiety. This is usually never the case, so you should eat until hunger is satisfied, not “to last”.

How to calculate the caloric content of food during interval fasting?

This diet does not require strict calorie counting and conditionally allows you to eat everything - most importantly, within the food window. But, of course, forget about common sense and the general principles of weight loss should not - on the excess calories few people manage to lose weight.

Doctors recommend calculating your daily “caloric” norm and make an approximate meal plan to get a useful and balanced diet. For calculations are usually used indicators of basal metabolic rate (BMR) and physical activity (TDEE), and the daily kcal rate is determined by special formulas that are easy to find on the Internet - for example, the formula Mifflin-St Jeor. The dietary goals are then taken into account: losing weight or maintaining a stable weight.

However, it is not necessary to fixate on these figures, because in most cases the food window simply does not allow you to overeat the daily norm (especially if it lasts 4-6 hours) - and this is an important advantage of interval fasting for women and men.

Contraindications to fast diet and its risks

Interval fasting is not suitable for all people. It should not be practiced during pregnancy and lactation, in children, adolescents or the very elderly. Other contraindications to this diet are:

• Digestive tract diseases;
• cholelithiasis;
• elevated uric acid levels in the blood and gout;
• insulin-dependent diabetes mellitus (in insulin-independent diabetes, it is necessary to consult a doctor first, as some “sugar” medications combined with periods of fasting can provoke the development of hypoglycemia - a sharp drop in blood glucose levels);
• eating disorders;
• weakened state - for example, after a serious illness or surgery;
• body weight deficiency.

Risks of fast diets:

• Overeating due to constant feelings of hunger (this is why nutritionists advise starting with “soft” regimens);
• significant fluctuations in blood glucose levels - an increase if you start your day with easily digestible carbohydrates, and a decrease if you eat an unbalanced diet or a too long food pause;
• psychological discomfort - if a person constantly feels hungry (and because of this - depressed or irritable), he should try a different diet;
• fatigue, lethargy - in this situation it is necessary to review the daily caloric content of food, perhaps it is too low;
• hypovitaminosis and lack of useful minerals (e.g. magnesium, iron) - this is a consequence of an unbalanced diet;
• metabolic slowdown - more often it occurs with long food pauses, to “shake up” the metabolism, you can try to change the scheme of fasting;
• digestive problems or hormonal failures - in this situation, doctors recommend reducing food breaks or switching to another diet.

With the right approach, interval fasting not only helps to lose excess weight, but can become a lifestyle. The main thing is not to be overzealous in losing weight and always keep common sense in mind.

The Liki24 team wishes you good health and ideal weight!