Intermittent Fasting – The Beginner’s Guide
Only Adults should try Intermittent Fasting and consult their physician before trying it.
Over the last three years, I have been doing various Intermittent Fasting techniques, and it’s great for my health. What led me to try this out was that having three meals a day started back in the industrial age to fit in with work; nowadays, it’s more like three meals plus snacks, which means our bodies are constantly processing food; we consume much more than our body needs.
Intermittent Fasting gives your body a much-needed break to clean up and restore; plus a way to lose weight and it has potential health benefits such as metabolic improvements and even improved brain functions.
In addition, Intermittent Fasting also reduces your Carbon Footprint, join us and become healthier while helping the planet.
- Use a Fasting Tracking App (with Gamification Features)
- Start with 12 Hour fast, then increase your fasting period to fit your lifestyle
- Have a day or two breaks from fasting on the Weekend
- Stay hydrated (Drink Water)
- Sometimes you just need something (Sparkling Water, Herb Tea, Cofee – no milk)
- Listen to your body, if you must eat, then eat (break the fast)
- Compete with yourself, not others (Everyone is different)
- Make healthy choices (avoid fast & junk food, sugary foods, and drinks)
- Combine with KETO for added weight loss and health benefits
Table of Contents
Although Intermittent Fasting has become a trend in recent years in the West, in reality, fasting has been a practice for millennia, not only in religious terms but also as a way to “purify” the body and improve health.
Indeed, more and more studies confirm that fasting is useful for losing weight and contributes to better health (1), and can even increase lifespan (2).
With this complete beginner’s guide, you’ll learn what intermittent fasting is and its pros and cons.
What is intermittent fasting?
As its name suggests, intermittent fasting is an eating strategy based on alternating periods when you can eat with periods when you don’t.
It isn’t a diet, but a meal program that, instead of indicating what you have to eat, tells you when you should eat.
As we already mentioned, fasting has been practiced throughout human history for religious and health reasons (for example, in ancient Egypt, India, and Greece). Indeed, there are numerous references to fasting in the sacred texts of the world’s main religions.
However, thanks to scientific research in recent decades, fasting has gained great popularity in many countries where it hasn’t been traditionally practiced.
The most important thing to note about fasting is that when done correctly, it has the potential to provide multiple health benefits, such as weight loss, metabolic improvements, and even improved brain functions (3, 4).
Different ways of doing intermittent fasting
Similar to traditional diets, intermittent fasting can also be a lifestyle. Actually, there are different ways to practice fasting, and each person can choose the method that best suits their needs.
Generally, the different methods vary in the number of fasting hours and the number of calories you can consume during the entire practice.
The fundamental principle behind all these methods is dramatically reducing your calorie intake; as long as you don’t consume excess calories at the end of your fast, you should lose weight.
Fasting for 12 hours
This method is convenient for beginners, as the fasting time is relatively short. All you have to do is go without food for 12 continuous hours each day. The best part is that you’ll do most of this fast while you sleep, which makes things easier.
A common example is eating your last meal of the day between 7 and 8 p.m. and fasting for 12 continuous hours until 7 or 8 a.m.
Some studies have shown that fasting for a minimum of 10 hours to a max of 16 hours per day is effective in releasing ketones into the blood and promoting weight loss (5).
This is another fasting method that is quite appropriate for beginners, as many people do it without realizing it.
The method consists of avoiding some food on certain occasions, specifically when you are not hungry. However, it’s also important that you follow a diet based on healthy foods.
The 16:8 method (very popular)
This method can be considered the next step for someone who has already tried the 12-hour method and, wants to increase the level of difficulty.
In the 16:8 method, people typically eat their last meal between 7 and 8 p.m. The next day, they skip breakfast and extend the fasting period to a maximum of 16 hours until lunchtime. Usually, men fast for 16 hours, while women fast for a max of 14 hours.
Some animal studies found that this method protected them against several conditions, such as diabetes and inflammation (6).
The 5:2 diet (very popular)
This method consists of consuming healthy foods as usual for 5 days of the week and fasting for only 2 non-continuous days. It’s recommended to take a day to eat normally after overcoming a day of fasting. During each fasting day, men can consume a maximum of 600 calories, and women up to 500 calories.
Although this method is quite popular among beginners, there is not much scientific research supporting it. Only a few studies have concluded that the 5:2 diet can effectively contribute to weight loss (7) and regulate blood insulin levels (8).
Alternate day fasting
This fasting method is quite tricky for beginners, and as the name implies, you must alternate fasting days and normal eating days throughout the week. However, there are several ways to practice this fasting method that can be combined according to the needs of each person.
One of the methods has you not eating solid food on fasting days. While another has you consume up to a max of 500 calories during these days.
On the other hand, on normal eating days, some people choose to eat as much as they want, while others limit their calorie intake. Some studies found that this method is effective for weight loss and maintaining and improving cardiovascular health (9).
The Warrior Diet
The Warrior Diet consists of eating just a few servings of healthy foods – such as fruits and vegetables – during a 20-hour fasting period, ending with a large meal at night within just 4 hours.
This fasting method is based on the belief that it’s healthier and more natural for humans to eat at night, as this fits perfectly with human circadian rhythms (10). Unfortunately, this is another difficult method to maintain in the long run.
Eat-Stop-Eat diet (Advance)
This is the most extreme method of intermittent fasting. This method is not suitable for everyone, as it can cause several side effects, such as fatigue, headaches, and irritability.
Basically, you don’t eat food for 24 continuous hours for one or two days a week. However, you can consume calorie-free drinks (tea, coffee, water) during fasting.
You can choose between starting the fasting period from breakfast or from lunch. At the end of the fasting period, you can gradually start consuming food as usual, with no limitations on the type of food you can eat.
How does it work in your body?
You can better understand the benefits of intermittent fasting when you know the metabolic pathways activated in your body to obtain energy when you go without eating for a certain number of hours.
First of all, after each meal, your body gets energy from the nutrients in the food you ate. The energy intake varies according to the type of food, whether it is carbohydrates, proteins, or fats.
If you consume more nutrients than your body needs, it takes the opportunity to replenish glucose (glycogen) and fat (triglyceride) reserves.
When you fast, after going 10 to 14 hours without eating, your body begins to use its stored energy reserves; for this, it activates a mechanism called hepatic gluconeogenesis (11) and uses the glucose reserves stored in the liver.
As these reserves are depleted, other pathways to obtain energy are also activated. At this point, lipolysis is activated – the breakdown of triglycerides in adipose tissue in the form of fatty acids – to use fat (ketones) as a primary energy source over glucose (12).
As the hours go by, gluconeogenesis continues to function to maintain a minimal supply of glucose, especially for the brain. However, the levels of ketone bodies in the blood will continue to increase and will be used as a source of energy by different body organs while you keep fasting (13).
If you fast longer, your body will start using more fats and ketone bodies as an energy source, and even the brain will begin to use ketones while blood glucose levels remain more or less stable (14).
On the other hand, fasting also activates a process known as autophagy, which your body uses to eliminate dysfunctional cells, reusing parts of them to create new cells. This mechanism serves to cleanse toxins and eliminate cells that are potentially harmful to health (15).
What is Autophagy?
Autophagy is a process by which cells break down and recycle their components. This can be done in response to nutrient scarcity, to get rid of damaged proteins, or simply as part of the cell’s normal life cycle. In all cases, autophagy is vital for cell health and function. When cells cannot break down properly and recycle their components, they become overloaded and start to malfunction. This can lead to a number of diseases, including cancer. Autophagy also plays a vital role in the development of new therapies for a variety of ailments. By understanding how autophagy works, scientists can develop medications targeting specific diseases by stimulating or inhibiting autophagy. In this way, autophagy is a promising target for treating many conditions, and why fasting is seen as a healthy habit.
An easy way to lose weight
Although intermittent fasting can provide multiple health benefits, it’s one of the best ways to lose weight, and most people do it with that goal in mind.
Several mechanisms come into play as a single process to enable weight loss through fasting. The basis of this process is a significant reduction in the number of calories consumed.
First, fasting helps increase the hormone norepinephrine (noradrenaline), a hormone that helps burn fat (16).
Simultaneously, growth hormone (HGH) levels increase significantly, which has benefits for both increased muscle mass and fat loss (17). In addition, another study showed that intermittent fasting causes less muscle loss than traditional diets that restrict calorie intake (18).
On the other hand, we must also consider that the glucose obtained from carbs can only enter fat cells through the hormone insulin. Therefore, fasting helps keep blood insulin levels low, which causes fat cells to start releasing previously stored excess glucose and use it as an energy source.
In addition, by notably reducing your calorie intake, you are consciously helping to regulate your appetite by suppressing the feeling of hunger (19, 20), which also allows you to have greater control over your eating habits.
By carefully analyzing all these principles, you can easily understand why fasting allows you to lose weight.
Benefits for your health
The following list of health benefits is based on the consensus obtained from studies carried out until recently.
However, although most of these studies point to enormous potential, it is crucial to remember that a good part of these studies is in their early stages. Plus, another part of the studies has been carried out on a limited scale, so new advanced studies are necessary to provide further support to these results.
- Weight loss
Intermittent fasting may be just as effective for weight loss as traditional diets based on lowering your daily calorie intake. The main advantage over these conventional diets is that fasting generally allows you to burn fat without worrying too much about the number of calories you consume daily (21, 22); of course, this is within reason, and healthy options are best.
- Insulin resistance
Fasting can dramatically improve your body’s ability to regulate blood glucose levels by reducing insulin resistance and increasing insulin sensitivity. This has a significant impact on the regulation and control of type 2 diabetes, to the point of notably reducing the need for insulin therapy (23).
- Cardiovascular Health
Several studies have shown the potential of fasting to regulate blood cholesterol levels. Specifically, fasting lowers “bad” cholesterol (LDL) levels while increasing good cholesterol (HDL) levels, something that helps decrease the risk of heart disease (24).
- Brain Health
Some studies have found a significant increase in the brain hormone BDNF, which contributes to the growth of new cells in the brain. Studies have also found a protective factor against degenerative diseases such as Alzheimer’s and Parkinson’s (25, 26).
- Less Inflammation
Some studies have found a relationship between fasting and lower levels of inflammation (27).
- Bonus: It helps you reduce diet stress
Many people who start dieting tend to stop due to the difficulties of maintaining it in the long run. In many cases, this is due to challenges in planning and preparing meals, often due to the fast pace of everyday life. One of the main advantages of fasting is that you don’t need to worry about planning, cooking, or cleaning food while you fast. In this way, fasting helps you lose weight while allowing you to be calmer and more relaxed.
General Side Effects
Everyone is different, the first time I fasted, I had headaches for 2 straight days. Here are some side effects:
- You can eat more than usual
When you spend a long period of time without consuming calories, it’s natural that you feel much hungrier than usual. The problem with this is that you can suffer an adverse psycho-physiological effect that leads you to consume more food than you usually do, counteracting the positive impact of losing weight (28).
Mild headaches are common when fasting, especially during the first few days, as the body has not yet adapted to changes in the diet (29).
- Negative mood changes
Low blood sugar levels during fasting can cause mood swings, anxiety, and low concentration levels (30).
Some people may also experience excessive fatigue during the first few days of a fasting regimen due to decreased blood sugar levels (31). However, this fatigue usually subsides as the body adjusts to fasting.
- Sleep problems
The decrease in sleep quality is one of the most frequent side effects during the practice of fasting, which can also contribute to worsening the feeling of fatigue (32).
- Nutritional deficiencies
Fasting for an extended period and then not replenishing your body with the proper amount of nutrients can lead to malnutrition and other health problems associated with extreme caloric and nutritional deprivation (33).
- Can I eat some food during intermittent fasting?
In general, fasting means not eating food and consuming calorie-free drinks such as water, unsweetened coffee, and tea without milk. However, some fasting methods have the consumption of small portions of low-calorie foods, such as fruits and vegetables.
- How effective is fasting for weight loss?
There is evidence that fasting is effective for weight loss, with an average of 7 to 11 pounds (3 to 4.5 kg) lost over ten weeks (35).
- Can I drink coffee while fasting?
Yes, you can consume moderate amounts of coffee during fasting, as long as it doesn’t include additives such as sugar or cream. There is also evidence that coffee can enhance the benefits of intermittent fasting (36).
- Does fasting cause muscle loss?
You shouldn’t worry about losing muscle if your fasting period doesn’t exceed 24 hours. There is evidence that regular fasting can promote muscle gain (17).
- Should Children Fast?
Fasting is not recommended for children and teens under 18 years of age, as it poses risks to their normal development due to the special metabolic demands of a growing body (33, 37).
Intermittent fasting is an eating program that, unlike traditional weight loss diets, emphasizes when you should eat rather than what you should eat.
There are several methods of intermittent fasting, and their main difference lies in the number of hours dedicated to the fasting phase, varying between 10 to 24 hours.
During fasting, hormonal and cellular changes favor eliminating fat and waste, which favors weight loss and specific health benefits.
In addition, intermittent fasting is an alternative to losing weight that is much simpler and easier to practice than many traditional diets.
It’s also not recommended for people suffering from certain chronic diseases or ailments since the practice of fasting can worsen these.
You should consult your physician before starting intermittent fasting.
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