Interval fastingis one of the most popular ways to lose weight in recent years.It has confidently overtaken the famous Dukan diet, the 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 scared - many people are happy to lose weight with interval fasting and don't even feel any discomfort.
This diet is also called interval dieting, periodic or cyclic fasting, and in English-language literature - intermittent fasting or fast diet.
Its roots are believed to date 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 by fasting. First of all, doctors at that time truly believed in its miraculous power and, secondly, such a treatment was certainly accessible to everyone. Indian yogis also refused food for a long period of time, thus 'cleansing' the soul and body.
What is interval eating?
As the name suggests, interval eating is alternating periods of eating and hunger. The time when you can eat without worrying about your weight is called the 'eating window'.
Where did the idea of interval fasting come from? It's thought 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) muscle relief. Unlike traditional 'drying out', interval eating isn't so harmful to the body - plus, according to studies, it's 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 on yeast fungi. It was later suggested that under conditions of starvation, a similar process takes place in the human body, and it is this process that promotes rejuvenation, health and 'enlightened' thinking activity.
In order to understand how interval fasting works, you need to have a good idea of where the body gets its energy for vital activity. Thus, in normal life, energy is supplied by glucose, into which food is converted after breaking down food and a series of biochemical processes. Part of the glucose is stored in the liver and muscle as an "energy reserve" - glycogen; in addition, our body does not forget about the NZ (inviolable reserve) of nutrients - adipose tissue.
If the body does not receive food for a certain period of time, it starts to use 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 state is called ketosis and is what promotes weight loss.
The basic principle of interval (fasting) nutrition is to artificially create periods in which the body is forced to expend its reserves and reduce body weight
Compared to other diets, intermittent fasting has a number of advantages:
- it doesn't require meticulous calorie counting;
- there's no need to carefully scrutinize the menu and look for quinoa, red fish and other expensive products in the stores;
- no need to spend a lot of time 'cooking';
- conditionally, you can "eat all you want" (of course, with reasonable restrictions).
Another difference of interval fasting is its benefits for the body, which have been confirmed in relevant studies. This diet is recommended not only by friends and bloggers, but also by nutritionists and doctors, especially endocrinologists. Interval fasting is widely used for weight loss, especially in metabolic disorders (e.g. reduced carbohydrate sensitivity).
Types of interval fasting
Traditionally, the following types of interval fasting are distinguished:
- 14/10, 16/8, 18/6, 20/4 (19/5) methods;
- the 5/2 method.
The first istime-restricted feeding (TRF) - for example, under the 16/8 scheme a person fasts for 16 hours, but can only eat for 8 hours - from 10 to 18.
The 5/2 fasting interval - this consists of eating according to the "anything goes" principle 5 days a week and fasting for 2 days. But in fact, this scheme does not require a complete refusal from food, and during the "hungry" days you can eat 500-600 kcal per day.
The most popular interval fasting scheme is 16/8. It is quite close to the standard diet and usually does not cause a person much discomfort.
The author of this scheme is Martin Berkhan. He received a medical education and then worked as a fitness trainer, so his diet is aimed not only at weight loss and general recovery, but also at creating relief for the body.
According to the 16/8 scheme, you can have breakfast at 10am and dinner at 6pm or 12 and 8pm respectively. It's better to choose the optimal time according to your biorhythms: for example, a lark will find it very difficult to go without food until midday, whereas an owl will hardly wake up at this time.
Important! Although it is possible to eat without restriction in the 'food window', this recommendation is conditional. Doctors and nutritionists still recommend following a healthy and balanced diet. If you eat 3 servings of fries with fatty pork bacon in 8 hours - it is unlikely that eating in between is beneficial for your body
The 5/2 method is ideal for people who don't want to monitor the "correctness" of their diet every day - it's much easier for them to restrict calories in 48 hours. This scheme is also indispensable when a person is working or studying - they choose their convenient "starvation" days.
There is an opinion that the 5/2 scheme may be suitable for athletes - provided that during the period of food break there is no training. However, this is more true for amateur athletes than for high-intensity professionals
Other interval fasting regimens:
- 14/10 (13/11) - the "milder" version, with a 10-11 hour food window;
- 6/18/6 - involves an 18-hour food window (e.g., 6pm to 12am);
- 20/4 (military diet) - starvation for 20 hours and a single meal with a snack, usually in the evening;
- eat-stop-eat method - abstaining from food for 24 hours (once or twice a week).
Is interval fasting helpful?
"Does interval fasting help" is one of the most frequently asked 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 website (PubMed):
- "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 fasting is indeed effective for weight loss. In addition, 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 unhealthy 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.
There is a relationship between interval fasting and health - and fortunately, in most cases, it is positive
"Amounts" of weight lost vary from person to person and depend on initial weight, comorbidities (e.g. metabolic syndrome, diabetes), chosen fasting diet and physical activity. According to the results of various studies, weight loss averaged 0.8-13% - this is considered a pretty good indicator, considering that in most cases the observations of people losing weight 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.
To avoid the discomfort of a constant feeling of hunger, you should rely on protein - beans, lentils, soy, chicken and turkey. Vegetables and fruit should also be an essential part of your diet - not just a source of vitamins, minerals, antioxidants and fiber, but also a "bulk meal" that fills your stomach and creates a feeling of fullness.
Easily digestible carbohydrates (cakes, pastries, sweet fizzy drinks) should be avoided as far as possible - they cause the development of insulin resistance and are of no particular 'use'. But this does not mean they should be completely abandoned. As a rule, all foods with easily digestible carbohydrates are tasty - which means they can be used as an antidepressant when a proper, healthy diet makes you feel too sad. The same goes for sugar and trans fats.
With the 16/8 pattern, there can be 2 or 3 complete meals. For example, at 12 o'clock you can have a breakfast of omelette with vegetables and wholemeal toast with avocado, at 15 o'clock - lunch of chicken fillet and buckwheat with salad, and at 19 o'clock - dinner of baked fish with boiled vegetables. Not the worst diet, is it?
With the military diet, the food window is only 4 hours, so nutritionists recommend moving it to dinner. For example, from 6pm to 10pm you can eat chicken with a side dish and salad and have a snack of fruit, nuts and yogurt.
It's also important to remember the following:
- The interval diet will only help you lose weight if you stick to it regularly. If you "starve yourself" correctly 3 days a week and eat without any interval 4 days, your body will start storing fat and your weight will skyrocket;
- whatever the interval - you need to drink enough. It's better to drink water, but sugar-free tea and coffee, non-caloric drinks (e.g. diluted juices) are also allowed;
- when choosing a portion size, be guided by your own feelings, not by when you feel 'hungry'. There is no need to overeat in the hope of prolonging satiety. This usually never happens, so you should eat until your hunger is satisfied, not "to last".
Please note: such a diet is not always given lightly, so nutritionists do not recommend starting with 'extreme' options. No one overrides adaptation, and the optimal interval fasting scheme for beginners is 14/10. From it you can gradually move to 16/8, 18/6 and even 20/4 (but only if really necessary). Fans of radical measures can try the 5/2 method. However, according to reviews, intervalized fasting is indeed more bearable if you "build up" the patterns gradually
You should also gradually return to your normal diet after weight normalization, but you don't have to give up intermittent fasting completely. The 10/14 and 8/16 schedules do not differ from most people's diets, except that they exclude harmful late-night dinners and late-night snacks. The main thing - remember that you need to introduce extra meals every few days and in small portions, so that the body doesn't start storing 'unexpected' food as fat
How to calculate the calorie content of fasting foods in intervals?
This diet doesn't require strict calorie counting and conditionally allows you to eat everything - most importantly, within the food window. But, of course, you must not forget common sense and the general principles of weight loss - few people manage to lose weight on excess calories.
Doctors recommend calculating your daily 'calorie' norm and making a rough meal plan to achieve a useful and balanced diet. Indicators of basal metabolic rate (BMR) and physical activity (TDEE) are usually used for the calculations, and the daily kcal rate is determined by special formulas that are easy to find on the Internet - for example, the Mifflin-St Jeor formula. Next, the goals of the diet are considered: losing weight or maintaining a stable weight.
For example, for a 42-year-old woman with a body weight of 71 kg and a height of 166 cm, leading a sedentary life, the TDEE is about 1652 kcal per day. If she wants to lose weight, she should reduce her daily calorie intake by 10-20% (1490-1320 kcal)
However, it is not necessary to fixate on these figures, because in most cases the food window simply does not allow you to exceed 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 fasting diet and its risks
Interval fasting is not suitable for everyone. It should not be practiced during pregnancy and breastfeeding, in children, adolescents or the very elderly. Other contraindications of this diet are:
- digestive tract diseases;
- cholelithiasis;
- high levels of uric acid in the blood and gout;
- insulin-dependent diabetes mellitus (in the case of insulin-independent diabetes it is necessary to consult a doctor first, as some 'sugar' drugs combined with fasting periods can cause hypoglycemia - a sudden drop in blood glucose levels);
- eating disorders;
- a weakened state - for example after a serious illness or surgery;
- low body weight.
Important! Some people are very sensitive to low blood glucose levels, so when fasting they may develop physiologic hypoglycemia with increased heart rate, sweating, changes in emotional state, tremors, presyncope or even unconsciousness. Such a diet is not suitable for them
Interval fasting and sports are also not very compatible, except for chess
Risks of fasting diet:
- Overeating because of the constant feeling of hunger (which is why nutritionists recommend starting with "soft" diets);
- significant fluctuations in blood glucose levels - a spike if you start your day with easily digestible carbohydrates and a drop if you eat an unbalanced diet or take too long a break;
- psychological discomfort - if a person feels constantly hungry (and because of this - depressed or irritable), they should try a different diet;
- tiredness, lethargy - in such a situation it is necessary to revise 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;
- slowing of metabolism - more often occurs with long food breaks, to "shake up" the metabolism you can try changing your fasting pattern;
- digestive problems or hormonal failure - 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 also become a lifestyle. The main thing is not to be overzealous in losing weight and always remember common sense.
The Liki24 team wishes you good health and ideal weight!