Today, most people are conscious about their weight. Thanks to this, a wide variety of weight loss methods, both modern and traditional, have become popular. This has led to the comparison of all of them and the constant search for the most effective approach. The intermittent fasting and caloric restriction are two of the methods featured in this debate.

Both approaches have a good scientific basis and expert support. They both have reasons why they could be better than the other. In order to better define an answer, in this article we will review the benefits of both methods, their effects, etc.

What is intermittent fasting? 

Intermittent fasting involves alternating periods of fasting, ranging from a few hours to more than a day, with periods of feeding. An example would be a fast lasting 16-20 hours, leaving 4-8 hours for one or two meals and possibly snacks. There are different ways to practice this type of fast , depending on the type of intermittent fasting you choose or the one that works best for you.

The different types of intermittent fasting 

There are different types of intermittent fasting. These are:

1. Time-restricted feeding

In this type of intermittent fasting, the individual chooses a limited number of hours in which they can eat. It could be between six and eight hours a day. Then you should only eat during these hours and not do it again for the rest of the day . 

2. Fasting on alternate days

It is similar to time-restricted feeding, with the only difference being that it is counted in days here. It is comprised of “free” days and “fast” days. In this type of fast an individual chooses a certain number of days in which he will go without eating or that he will not ingest the minimum calories required by the body. 

These are the days of fasting. The rest of the days, the individual can eat as much as he wants without restrictions. These are the days off. The fasting days and days off in this type of intermittent fasting alternate, hence the name of alternate-day feeding.

3. 5: 2 meal pattern

Unlike alternate-day fasting where feeding and fasting occur on alternate days, here, the feeding and fasting days are continuous . What does this mean? It means that there is an unrestricted diet for five days in a row, followed by two days of restricted calorie intake.

4. Periodic fasting

In this approach, a person chooses a period of consecutive days in which to restrict their food intake, followed by a period of feeding. An example would be to have six consecutive days of restricted eating during the month, and the rest of the days could be without restrictions. 

It could even be two periods of restricted eating in a month. It all depends on the needs of the individual.

5. Fast of 24

This is a type of intermittent fasting where you go a 24-hour period without eating. This can be done once or twice a week.

People who should refrain from intermittent fasting 

As with any other diet, there is something very important to keep in mind; intermittent fasting is not for everyone . Intermittent fasting is not recommended if:

  • You are pregnant. This is because pregnant women need a lot of calories to maintain their pregnancy. 
  • You have a history of eating disorders.
  • You don’t sleep well or you suffer from insomnia.
  • You are new to the world of diet and exercise.
  • You have complicated diabetes.

Benefits of intermittent fasting 

The most common benefit of intermittent fasting is weight loss . This is due to the long periods of restricted eating that one is subjected to, as one normally begins to burn fat after 12 hours of fasting.

What is calorie restriction?

Unlike intermittent fasting, where you go hours or even days without eating, calorie restriction is quite different. Calorie restriction is all about consistency and involves a significant reduction in the amount of calories you consume each day . 

Let’s say if you used to consume 3000 calories a day, you will have to lower it to 2500 or even 2000 calories a day. Caloric restriction is basically reducing the average daily calorie intake below what is typical or usual, without reaching a state of malnutrition or depriving yourself of the essential nutrients that your body needs. 

Benefits of calorie restriction

Caloric restriction offers several benefits such as weight loss . If your body needs 2,500 calories daily, consuming 2,000 calories every day will make you lose weight, since you will be consuming less than you need, which will force your body to use stored energy in the form of fat. 

Long life expectancy . Studies of people who practice calorie restriction found that these people have reduced levels of risk factors for cardiovascular disease and diabetes.

How to Follow a Calorie Restriction Diet

These are the things you must do to reach your ideal weight through calorie restriction:

  1. You have to start looking at food as fuel. This means eating only the foods you need to function properly, not eating until you feel full.  
  2. You must get enough sleep. Lack of sleep could cause you to break your diet, as you would be more susceptible to eating things like late-night snacks, which you should avoid at all costs. 
  3. Prioritize calories and go to bed a little hungry. Your first meal of the day should be larger and full of protein. This helps prevent cravings later in the day and therefore helps you stick to your diet. 
  4. Keep in mind that it will be a great challenge. Weight loss is not easy. This is something to keep in mind as you move into this focus. 
  5. Eat foods that are very nutritious. Needless to say, eat foods that provide your body with all the necessary nutrients. Incorporate vegetables, fruits, vegetable proteins, healthy nuts, etc. in your diet

Weight loss from intermittent fasting vs calorie restriction

Most people have always opted for calorie restriction when it comes to losing weight. Many believe that calorie restriction is effective, because when you practice it all you need to do is make sure you are consuming fewer calories than you consume on a daily basis. 

Each person has a certain amount of calories that they need to consume every day. In calorie restriction, as long as you consume 500 fewer calories than your body needs , you should experience weight loss.

Intermittent fasting works the same way as calorie restriction, focusing more on weekly calorie averages than daily calorie averages. As mentioned earlier, intermittent fasting involves selecting periods when you will not eat or eat the least the body needs for normal function during fasting hours or fasting days. 

On the other hand, during the feeding days or hours, you can eat as much as you can or want. Intermittent fasting also results in weight loss . The question that then comes to mind is, between intermittent fasting and calorie restriction, which approach works best when it comes to weight loss, which is easier to follow, and so on.

An experiment from the University of Illinois

It would be difficult to know for sure which of these two approaches is more effective in terms of weight loss if there were no experiments that directly compared them. However, the University of Illinois conducted an experiment to clarify this argument once and for all. 

In the experiment, they compared caloric restriction to alternate-day fasting, which is a type of intermittent fasting. In the alternate-day fasting method, the individual has a fasting day in which he consumes only 25% of his usual intake and alternates it with “off” days in which he is allowed to consume as much food as he wishes. 

The duration of the experiment was 12 months. It was at the University of Illinois at Chicago. Participants were recruited from the Chicago area through elaborate leaflet advertising and were assessed using questionnaires, body mass index assessment, and a pregnancy test was also performed. 

The individuals ranged in age from eighteen to sixty-five years. Their body mass indexes ranged from 25.0 to 39.9. Both genders were included in the study.

About the study participants

The study participants were divided into three groups. The first group belonged to people who would fast on alternate days . The second group belonged to people who would practice the caloric restriction diet . The last group had no limitations because it was a control group. The experiment was carried out in two phases. 

The first phase, which was the first six months, was for weight loss and the second phase, which was from month seven to twelve, was for weight maintenance. This is because they didn’t just want to measure which approach is most effective when it comes to losing weight; They also wanted to know which one is effective in maintaining weight loss . 

Participants were also told not to change their physical activity routine as this would affect the results.

Intermittent fasting and calorie restriction during the weight loss phase 

During the first three months, individuals in the alternate-day fasting group (intermittent fasting) and the caloric restriction group received all of their meals. They also received dietary advice. Individuals were required to reduce their intake by 25% during this weight loss period. 

On fasting days, individuals had to consume only 25% of their daily intake at lunch and on days off they had an intake of 125% divided into three meals. The calorie restriction group was instructed to consume 75% of their energy intake divided into three meals. The meals consisted of 60 percent carbohydrates, 30 percent fat, and 10 percent protein.

During the weight maintenance stage, individuals in the intermittent fasting group had to consume 50% of their daily energy needs during fasting days and 150% divided into three meals during free days. 

Individuals in the calorie restriction group had to consume 100% of their energy intake during this period divided into three meals. The control group was instructed not to change their eating or physical activity habits throughout this period.

The results of the study

From the results, there are some important aspects that we must consider. These aspects include dropout rate and weight change . The dropout rate could indicate which of the two approaches is easier to follow, and the weight shift could show which is more effective in losing weight.

Of the 100 participants, only 69 were able to complete the study. The dropout rate was higher in the intermittent fasting group. Thirteen of the thirty-four dropped out. The calorie restriction group had ten dropouts of the thirty-five participants. The control group experienced a dropout of eight individuals out of thirty-one individuals. 

People who dropped out of the intermittent fasting group said it was due to difficulties continuing the diet. Regarding weight loss, there was not a big difference between the two groups : the alternate day fasting group experienced a total weight loss of 6%, while the calorie restriction group experienced a weight loss of 5.3 %.

This suggests that there is no one best method. It all depends on each individual. Can you handle intermittent fasting or daily calorie restriction? What advice has your dietitian given you? If you are having trouble selecting the best approach for you, it is advisable to consult an expert , as he or she can help you choose the one that best suits your needs. 

By Dr. Eric Jackson

Dr. Eric Jackson provides primary Internal Medicine care for men and women and treats patients with bone and mineral diseases, diabetes, heart conditions, and other chronic illnesses.He is a Washington University Bone Health Program physician and is a certified Bone Densitometrist. Dr. Avery is consistently recognized in "The Best Doctors in America" list.

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