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Intermittent fasting: How effective is it?

by | May 11, 2021 | Intermittent Fasting | 0 comments

A review of the diet known as intermittent fasting.

Someone claim, this diet that it promotes:

  • weight loss
  • reduction of blood pressure cholesterol
  • levels
  • inflammation
  • improves brain function
  • it protects against cancer
  • helps to reduce blood sugar
  • and finally simply prolongs the life

All these statements are primarily from the lips of celebrities or science articles.

I will share the scientifically proven facts about this diet.

The essence of nutrition with intermittent fasting is that Periods of complete refusal of food usually from 12 hours alternate with periods when a person eats typically without limiting food and fullness.

The modern diet has several types:

  • 6 / 18 hours
  • 8 / 16 hours
  • 18 / 36 hours
  • 24 / 24 hours
  • food every other day
  • and a two-day / 5-day system

The first digit is the number of hours you can eat, and the second digit is the time of fasting.

For example:

Eating 8/16 means that eating allows only for 8 hours a day, then fasting for 16 hours. And so it repeats itself from day to day.

Eating 2 / 5 days means that two inconsistent days a week, you need to fast again for days to eat as usual. The name of the time when you can eat is the eating window

How does this Intermittent nutrition work?

Let’s first understand what happens when you are completely hungry. Approximately I start with 12 hours of fasting, the glycogen reserves in the liver and muscles begin to come to an end. When the glycogen stores are depleted, the body starts to use fat for energy production. Blood glucose levels drop by more than 20 percent. And ketone bodies begin to be produced, which serve as fuel for all the body’s needs.

Fasting leads to:

  • changes in the metabolism of
  • intracellular processes
  • and the level of certain hormones
  • improves sensitivity to insulin
  • decreases blood pressure
  • Reducing of fat reserves
  • blood glucose levels drop
  • and inflammatory processes subside
  • and the level of bad cholesterol decreases

in laboratory animals, fasting improved:

  • the course of type 2 diabetes mellitus,
  • oncological diseases
  • and diseases of the cardiovascular system

Does it prolong life?

Also, fasting in the experiment increased the life expectancy of rodents by 30%.

It turned out that fasting causes activation of those internal cellular mechanisms that are responsible for aging. It was found that energy deficiency stimulates the processes of autophagy. Such a phenomenon is when inside the cell and disintegrates and removes harmful particles of waste products.

Stimulation of autophagy processes is one of the means of prolonging life. The lack of energy also helps to protect the genetic material from mutations. And therefore reduce the likelihood of cancer. It turned out that for the stake to work fully for all its positive effects, you need to limit the number of calories by 20%. That is, you do not need to finish eating.

This strategy is suitable for a person who wants to lose weight. But it is not ideal for the long term and for people who want to improve and maintain their health.

On such a diet, you will not last long. The solution came when it was understood that the beneficial effect of hunger begins around the twelfth hour. Suppose you do not eat for more than 12 and 14 hours and then eat anything at will, well, almost. The body develops the same positive effects as with complete fasting. But at the same time, the person does not suffer much and does not lose weight.

With this approach, you can follow the regime for a very long time without harming your health.

What approaches to intermittent fasting work better, and do intermittent fasting work at all?

I found a recent paper in the journal “Nutrition.” The results of numerous studies on different types of intermittent fasting are collected.

Regimen two days a week fasting five days a week eating results in:

  • weight loss
  • improved insulin sensitivity
  • improved biochemical health indicators
  • and reduced blood pressure

Regimen 24 after 24 hours

here, the data is very contradictory.

First study, healthy built-in men did not change any indicators at all.

Second study, overweight men lost 5.8% of their weight.

Third study, the weight did not decrease, but the insulin sensitivity improved.

8/16 hour regimen:

  • reduced body fat content
  • preserved muscle mass
  • improved biochemical health indicators in men who were engaged in strength training

In another study, such a regime did not cause any changes, neither good nor bad. And at the same time, all the modes of intermittent fasting worked well in laboratory rats.

Another study was published in December 2019 in the journal “Cell.”

People with metabolic syndrome under test.

Metabolic syndrome is a condition in which a person simultaneously has high:

  • excessive fat deposition
  • high blood pressure
  • high blood sugar
  • higher cholesterol or triglycerides

Before starting the study, these people ate for an average of 15 hours a day.

They were asked to eat only for 10 hours without changing their diet at all.

Participants started eating at 8/10 am and stopped eating at 18/20 am.

Accordingly, people followed them for 12 weeks. The number of participants was 19 people:

  • Weight decreased by 3% on average.
  • on average, the waist size decreased by four centimeters
  • the blood pressure reduced
  • the level of bad cholesterol fell

In the study, there was no control group involved.


The benefits of intermittent fasting do not have sufficient evidence.

Conflicting results may occur because those different people ate different amounts of food during the limited eating window.

Everyone has different digestion. Someone can swallow a lot in one sitting. And someone can not eat more than a certain amount.

It will determine the differences in the daily intake of calories. The less a person ate during the eating window, the better the effect and vice versa.

Is there any harm from intermittent fasting?

in general, no. the question is open only to people with

gallstones or with a violation of the George

excretory system

Theoretically, losing weight at the initial stage can lead to changes in the composition of bile and an increase in cholesterol levels. Hence the formation of stones.

Also, during fasting, the bile of the debt stagnates. And it can form sediment. These two factors act in the same direction. Only the development of stones never begins in a healthy person without prerequisites.

Normally, even during fasting, people swallow saliva and drink water, which stimulates bile production, preventing stagnation.

Still, it will not be superfluous to do an ultrasound before starting intermittent fasting.

Would I recommend intermittent fasting for health?

Yes. as an alternative to a very healthy diet with many restrictions.

Mainly because this food is easily doable, the effect of any food is primarily based on whether a person can adhere to it or not.

There are no restrictions on the quantity and quality of food. You don’t have to think about what you can and can’t constantly do.

A precise eating window time is easily doable. Do not, for example, get attached to certain hours of breakfast, lunch, or dinner. It is allowed to eat when you want as much as you want.

The 8 by 16 mode is optimal. The eating window should be placed as early as possible to start eating from 7/8 in the morning and finish at 15/16 hours.

If you want to lose weight, you can do this.

For the reduction period, stick to the eating window of 6 hours and then go to 8 hours for maintenance. 

Why is the eating window better to do in the morning, after lunch, and before bedtime?

First: more energy is spent during the day than at night. Therefore, if you eat before 15:00, it is conditional. There is a chance that you will spend these calories. If you eat in the evening, then during sleep, the energy expenditure is minimal, and it will transfer fat. 

Second: eating increases the level of insulin increases the production of cholesterol. Interestingly, the most active cholesterol is synthesized at night. We stimulate this process with more insulin and get fresh bad cholesterol in the morning.

Third: during the day, people want to eat less and do not overeat and in the evening, on the contrary.

Fourth: our body works differently during the day. In the morning and the afternoon, the metabolic processes are more active. The levels of hormones and digestive enzymes are such that even relatively junk food is safe. In the evening, the metabolism slows down.

Suppose you want to learn more about how the time of eating affects the effect of nutrition. Go to the article where I talked about the study when people ate in the morning from 8 to 2 pm. And what the results were. 

To learn more:

Intermittent fasting 6:18 How time is important?

Although with intermittent fasting during the eating window, you can eat whatever you like. It is necessary to approach nutrition wisely.

under all conditions, exclude:

  • fast food
  • sausage
  • cheese with palm oil
  • and so on

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