Intermittent Fasting

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What is Intermittent Fasting?

It is a dietary model recommended chiefly for people who want to lose weight. Fasting means a period without food. Usually, fasting was associated with stopping eating for as long as possible and eating as little as possible. This dieting method is unhealthy, as it needs to provide the necessary ingredients, which can be dangerous.

However, intermittent fasting is not harmful to starvation.

Intermittent refers to periods of eating that alternate with periods of fasting. Depending on the specific IF model, it happens at various intervals. The period during which we eat is called the “eating window.” According to this method, we should adjust our fasting and eating times according to our lifestyles and preferences. Experts confirm intermittent fasting has many health benefits.

Intermittent Fasting: Beginner's Guide

Intermittent Fasting Models

The proper diet must be selected to meet a person's individual needs—factors such as gender or age. Also, diseases and lifestyles are considered. Intermittent fasters can eat and drink caloric food, but a period of eating is followed by a period in which nothing can be eaten. Specific hourly intervals determine these periods and should remain constant. The number of fasting periods depends on the particular IF model. There are various types of intermittent fasting. The two main ones are TRF and ADF.

Time-Restricted Feeding

TRF Model (8:16) – This intermittent fasting model is a variant in which meals can be eaten for 8 hours, and the next 16 hours represent fasting. It is essential to maintain the eating window, always at the same hour. For example – you eat breakfast at 9 a.m. Then, 8 hours of fasting. You can eat your next meal at 5 pm.

It would be best if you stuck to it strictly. It means that if you miss a time gap for eating, you must wait until the next. Arrange meals voluntarily, tailored to your needs. Take into account your daily rhythm. What time do you get up? And what time do you go to bed? It is essential to follow the ratio: 16 hours of fasting, 8 hours of eating window.

Alternate Day Fasting

ADF Model (5:2) – In this model, the period of abstinence from food, in turn, applies to entire days. Twice in one week, 24-hour fasts are carried out. However, eating without a food window for the remaining days is possible. However, in this case, fasting does not always mean giving up meals altogether; it is about a significant reduction in calories.

During fasting days, there must be a significant caloric reduction. Some people keep a fast and eat nothing all day. Only liquids can be taken during the 24-hour hunger strike. Some versions of the ADF allow you to eat low-calorie meals. Then, you can stay under 25% of your daily caloric needs. Options for setting fasting days vary depending on your preference.

The most popular version of the TRF window diet is 16/8 intermittent fasting. For most people, this method of conducting intermittent fasting is fully applicable, as it can be turned into a habit. The time interval of the dietary window is individually determined under the needs and responsibilities of the person following such a dietary model.

Besides, it allows for reasonable intervals between meals, and as a result, usually on intermittent fasting 16/8, one eats three meals a day. On the other hand, the ADF method works well for busy people who find it hard to adjust to an hourly schedule.

What Can You Eat During Intermittent Fasting?

Intermittent fasting is not a diet that allows or disallows certain types of meals. It is a schedule-based dietary model – its method is based solely on intervals. In the IF, there are no commands or bans on food. However, healthy eating during eating intervals is recommended. Regular meals can be eaten, covering the entire day's energy needs within eight hours.

IF can also be combined with any diet. Meals should be varied, with a limitation of highly processed foods. The number of meals depends on our individual needs. It is essential in intermittent fasting to adhere to set times, to eat meals always at the same time, and to do fasts at specific intervals as well.

Intermittent Fasting: Beginner's Guide

Effectiveness of Intermittent Fasting

Whether a diet or dietary pattern works depends on the body's needs. However, many people have become convinced of the effectiveness of intermittent fasting, and they have noticed health benefits and rapid weight loss. Experts have noted fasting allows rapid fat loss and causes valuable processes, such as cell repair or lowering insulin levels.

Intermittent Fasting and Cell Repair

Interval eating is related to autophagyTrusted Source, a significant discovery in science and dietetics. Yoshinori Ohsumi – This Japanese scientist describes autophagy. In 2016, he received the Nobel Prize for it. His work over the years has made us more knowledgeable about cellular processes occurring in the human body.

Autophagy – intermittent fasting is based on autophagy. It is a catabolic process that involves the controlled breakdown of unneeded cells. Autophagy is a natural biological process; it is not dangerous to health, on the contrary. It is the body's self-cleaning process. The body's cells can constantly be left to undergo damage. It promotes the development of disease states and dysfunctions within many systems.

The autophagy method allows the body to eliminate damaged, abnormal, or pathogen-infested cells. Through autophagy, cells permanently break down their unnecessary elements and facilitate the growth of new cells. Maintaining balance in this area prevents disease. Activating the autophagy process in the organism can alleviate inflammation and optimize the body's biological functions.

Intermittent Fasting: Beginner's Guide

What negatively affects the autophagy process?

What positively affects the process of autophagy?

Physical activity positively affects autophagy by lowering stress levels and flushing toxins out of the body through sweating. It also initiates regenerative processes, which cause cell renewal.

During fasting, autophagy gains momentum, a lot of energy is released, and tissue repair processes occur. Through these mechanisms, intermittent fasting contributes measurably to improved health and well-being. This is why a model like intermittent fasting is effective and recommended by nutritionists.

Intermittent Fasting and Lowering Insulin

That fasting affects lowering blood sugar was noted many years ago. It is prompted by logic – eating raises this level, so the most effective way to reduce it would be to avoid eating. After the first 24 hours, you can notice the effects. On the other hand, regular implementation of intermittent fasting can have more long-lasting results.

Conducting a fast for some time affects tissue sensitivity to insulin; the body handles glucose better. It is very beneficial for people with insulin resistance and diabetesTrusted Source. Lowering insulin levels gets rid of water and salt from the body. It, in turn, causes a reduction in complaints of bloating. Studies have recently recognized intermittent fasting as an acceptable method of lowering insulin levels.

Remember, if you suffer from medical conditions, do not start a drastic diet alone. First, consult a specialist – a doctor or nutritionist. Having problems with blood sugar regulation, the sudden lowering of insulin may not be beneficial either. It depends on the case, so you are always cautious to stay safe in any drastic dietary changes.

Intermittent Fasting and Weight Loss

Intermittent Fasting: Beginner's Guide

The intermittent fasting method is ideal for people who want to lose weight. So, how does intermittent fasting affect fat loss? Intermittent fasting causes various changes in the body. It makes it easier to lose body fat while there is an increase in muscle mass.

The human body has developed mechanisms to cope with periods of unavailable food. There is then a switch from burning glucose to burning fat. Fat is simply a store of energy. Then, the body uses up all its fat reserves, which get burned.

Growth hormones make fat more available for energy. It also helps maintain muscle mass and bone density at appropriate levels. Its production decreases with age.


Intermittent fasting has a beneficial effect on the functioning of the body. However, it must be adequately planned and observed. If intervals are taken care of, the impact of intermittent fasting may be improved. Otherwise, the phenomenon of autophagy, the critical process here, will not occur. To see what the basic rules of intermittent fasting are so that you can avoid any mistakes.

Intermittent Fasting: Beginner's Guide
  1. In intermittent fasting, no rigid restrictions exist on what food to eat. You choose what meals you eat for yourself. But healthy eating should not be ignored by you. Otherwise, you may expose yourself to vitamin and different nutrient deficiencies. Remember to adjust according to your caloric needs.
  2. One can drink water, herbal infusions, fruit teas, and coffee during fasting. However, these types of drinks must not contain sugar or sweeteners. You can't drink fruit, vegetable juices, milk, and milk products, as it is a calorie-rich beverage.
  3. The designated fasting time and eating time must be strictly observed. Therefore, it is better to prepare meals in advance. If you don't manage to eat during the eating period, you must wait another eight hours until the next such period (in the case of the TRF method).
  4. The ADF method involves fasting or eating low-calorie meals for 24 hours. The caloric content of these meals must be – about 500 kcal for women and 600 kcal for men.
  5. Supplements can be used during intermittent fasting. But first, check the composition of the supplements to see if they contain any caloric additives. If the supplements provide calories, they interrupt the fasting period, negatively affecting the effect.
  6. Physical activity and exercise promote the effects of fasting. However, care should be taken to do moderate workouts. At the beginning of intermittent fasting, fatigue and lack of energy may bother you more. When consuming fewer calories, the workout should be adjusted accordingly.
  7. There are no time determinants about how long you can do intermittent fasting. You can be on IF for as long as possible if you provide nutrients. Keeping the diet properly ensures that there are no health dangers.
  8. It is not recommended to consume alcohol on intermittent fasting. Nutritionists recommend that you give up alcohol and smoking completely. After all, if you are introducing a diet, it must be mostly about your health. But alcohol is allowed in the eating window if you do not want to quit it.
  9. Intermittent fasting is not the recommended dietary method for everyone. Some people should not use long-term fasting, which can cause health problems. It includes pregnant women, children, or people with chronic illnesses. Any change in diet should also be consulted with a doctor.

Health Benefits

Intermittent fasting has beneficial effects on physical and mental health. Clinical studies confirm it. In addition, bringing in fasting affects weight loss, which, for many people, is the primary goal of using this dietary model. During fasting, the digestive system has time to regenerate. It improves the functioning of many vital organs in the digestive system. Fasting also keeps the body from secreting insulin. The benefits of intermittent fasting are as follows:

Intermittent fasting has many health benefits. One of them is its effect on reducing insulin productionTrusted Source. This process reduces appetite. It also reduces the risk of metabolic diseasesTrusted Source, such as diabetes and insulin resistance. Intermittent fasting lowers blood sugar, which can help control sugar. However, people with medical conditions should first consult their doctor about the possibility of intermittent fasting.

IF has a positive effect on lipidogram results. A lipogram is a test done from a blood sample that examines various fractions of cholesterol and triglycerides, and better cholesterol results protect against cardiovascular diseasesTrusted Source such as atherosclerosis.

Intermittent fasting generally increases immunity and better regeneration of the bodyTrusted Source, which has an excellent protective effect against disease and inflammation. The body is better protected against bacteria, viruses, and other pathogens.

In addition, intermittent fasting also has a good effect on the brain. This is because it improves long-term memory. Studies have shown that IF contributes to forming new neurons in the hippocampus region, improving memoryTrusted Source. Intermittent fasting also enhances brain function. However, more research is needed to confirm this.

Overall, intermittent fasting is good for mood. Thus, it is because it regulates the body's functioning – it positively affects essential functions like bowel movements and sleepTrusted Source. In addition, autophagy causes old, damaged proteins to be broken down and removed and new and wholesome proteins to take their place, which delays aging.

Intermittent Fasting: Beginner's Guide


Because of its health benefits, intermittent fasting is especially recommended for certain groups of people. Among other things, this dietary model is an effective way to lose weight. See for whom intermittent fasting will be particularly advantageous.

People who want to lose weight are the main target of intermittent fasting. This fasting is a healthy and effective way. It is also an easy way to assimilate because it is not restrictive about food. All you have to do is observe periods of eating, fasting, and not exceeding calorie standards.

Intermittent fasting is also a good idea for people with irregular lifestyles. Bringing in some rules and habits helps to get your diet in order. It allows such people to control calories better. By setting a schedule, they will also improve the quality of their sleep and regulate bowel movements.

Snacking – some people have problems with it. Sometimes, it is the leading cause of weight gain. Elevated blood sugar affects a greater appetite and causes overeating. Bringing intermittent fasting can help them with this, as it lowers sugar in the blood, suppressing appetite. However, the presence of any diseases requires the doctor's opinion on introducing a diet.


Any diet or dietary model can adversely affect health when misused. Therefore, making any lifestyle changes after a medical consultation is always advisable. Available nutritionists are good for helpful advice and set individually tailored menus as part of their profession. It is worth taking their help since everybody is different and has different needs.

It is also worth considering whether intermittent fasting is a suitable method that you can handle. For many people, it can cause various problems. Matching your diet to your needs can be difficult. Often, there may be a situation where poorly chosen meals won't give you energy and cause fatigue.

Improperly balanced meals can lead to vitamin and mineral deficiencies, especially with long-term use of this nutrition method. On the other hand, overly generous meals eaten at set periods can hurt the stomach and cause bloating, constipation, or heartburn. It is also improper to plan meals so that you eat late, just before bedtime.

Some groups of people should not use intermittent fasting due to its nature. Fasting produces positive changes, but it can also increase health risks in certain conditions. Here are the groups of people who may be harmed by intermittent fasting:

Intermittent Fasting: Beginner's Guide

Pregnant women must be cautious about their health—also women who are breastfeeding. The comeback of weight after pregnancy and childbirth is a problem for many women, but intermittent fasting is not recommendedTrusted Source.

Long periods of not eating when calorie requirements are higher than average, and thus during lactation, can cause weakness and feelings of lack of energy. Studies have shown that fasting longer than 24 hours reduces milk production. Therefore, it is better to avoid the 5:2-day version of fasting.

Intermittent fasting has many benefits – including repairing the cells that protect the body. But if losing weight is dangerous for you, giving up this way of increasing immunity is better. It can lead to anemia, which can sometimes be hazardous.

Also, people with various medical conditions must be careful about intermittent fasting—for example, people with gallstonesTrusted Source. In gallstone diet, it is essential to normalize body weight. An excessively caloric diet poses a significant risk of liver colic attacks.

However, rapid weight loss using energy-poor diets is also contraindicated. Therefore, long-term intervals of non-eating contribute to the retention of bile in the gallbladderTrusted Source. For those with chronic illnesses and those who train intensively, consult a doctor or nutritionist before using intermittent fasting. Any drastic change in diet should be made prudently, as it affects overall health.

Also, keep in mind that improperly used intermittent fasting can become a cause of weakness and decreased energy. States of irritability are standard, especially for the first few days after the introduction. Some people may also experience headaches and dizziness. In addition, long-term fasting can become a cause of anemia.


The prevalence of obesity in the United States continues to rise, so new diets and diets are receiving special attention. Intermittent fasting has recently been a trend in diet topics. It involves alternating periods of eating with periods of dieting. Depending on the pattern, they occur according to sixteen hours of fasting, eight hours of eating, or two days of fasting per week. Intermittent fasting is mainly based on strict adherence to periods of eating and fasting.

However, there are no specific rules regarding the food consumed. Only during the fasting period are high-calorie drinks not allowed. Intermittent fasting is very effective and beneficial to health due to the process of autophagy. Autophagy is a metabolic process that breaks down damaged and abnormal cells in the body. It has many positive health benefits, like affecting the immune system and protecting against disease.

This type of fasting is especially recommended for obese people concerned about healthy weight loss. However, certain people should not use intermittent fasting; among them are pregnant women. Any change in diet should be consulted with an expert. Because an improperly chosen diet can very negatively affect health, it is better to be careful.


June 6, 2023
16 minutes read

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