April 30, 2019

The basics of intermittent fasting - the ultimate beginner's guide

Das Einmaleins des Intermittent Fasting — Der ultimative Anfänger Ratgeber

Intermittent fasting is one of the world's most popular health and fitness trends at the moment. People are using intermittent fasting to lose weight, improve their health and simplify their lifestyle. Many studies have shown that this dietary strategy can have powerful effects on your body and brain and could even help you live longer (1, 2).

What is Intermittent Fasting (IF)?

Intermittent fasting is a dietary pattern that alternates cyclically between periods of eating and fasting. It does not specify which foods should be eaten, but when you should eat. In this respect, intermittent fasting is not a diet in the conventional sense, but more of a nutritional scheme. Common intermittent fasting methods include daily fasting for 16 hours or two fasting periods of 24 hours per week.

Fasting has been practiced throughout human evolution. Ancient hunter-gatherer cultures did not have supermarkets and refrigerators, which meant that they did not have food available all the time. Sometimes they could not find anything to eat. As a result, humans have evolved to be able to function without food for long periods of time.

In fact, occasional fasting is more natural than always eating 3 to 4 (or more) meals a day. Fasting is often practiced for religious or spiritual reasons and is part of most religions including Islam, Christianity, Judaism and Buddhism.

Intermittent fasting methods

There are a number of different ways to practice intermittent fasting, all of which involve dividing the day or week into periods of eating and periods of fasting. During these fasting phases, you either eat very little or nothing at all.

The most popular methods are:

The 16/8 method: this method, also known as the Leangains protocol, involves abstaining from breakfast and limiting your eating phase to 8 hours per day, such as from 1pm to 9pm. Following this, you fast for 16 hours.
Eat-Stop-Eat: This method involves two weekly fasting phases lasting 24 hours. You could, for example, not eat anything from lunch on day 1 until lunch the next day.
The 5:2 method: With this method, you only consume 500 to 600 kcal on two non-consecutive days per week, while eating normally on the remaining 5 days.

By reducing your calorie intake, all of these methods should result in weight loss if you do not compensate for the reduced calorie intake during the eating periods.

Many people consider the 16/8 method to be the easiest and most sustainable method. It is therefore not the most popular intermittent fasting method for nothing.

How intermittent fasting affects your cells and your hormones

When you fast, a whole range of things happen in your body on a cellular and molecular level. For example, your body adjusts its hormone levels to make stored body fat more easily accessible. Your cells also initiate important repair processes and change the expression of your genes.

Here are some of the changes that occur in your body when you fast:

Growth hormones: your natural growth hormone levels can increase dramatically, up to fivefold. This has numerous benefits for fat loss and muscle building (3, 4, 5, 6)
Insulin: Your insulin sensitivity will improve and your insulin levels will drop dramatically. Lower insulin levels make stored body fat more accessible (7).
Cellular repair: In a fasted state, your cells initiate cellular repair processes. This includes autophagy, where cells break down and digest old and dysfunctional proteins that have accumulated in the cells. (8, 9)
Gene expression: Changes occur in the functions of genes that are associated with longevity and protection against disease. (10, 11)

These changes in hormone levels, cell function and gene expression are responsible for the health benefits of intermittent fasting.

An effective fat loss tool

Weight loss is the most common reason people try intermittent fasting (12). As you eat fewer meals, intermittent fasting can lead to an automatic reduction in calorie intake. In addition to this, intermittent fasting alters hormone levels to promote weight loss.

As well as reducing insulin levels and increasing the body's natural release of growth hormone, intermittent fasting increases the release of the fat-burning hormone norepinephrine (noradrenaline). As a result of these hormonal changes, short-term fasting can increase your metabolic rate by 3.6 to 14% (13, 14).

By helping you eat less and burn more calories, intermittent fasting can induce weight loss by changing both sides of the calorie equation. Studies have shown that intermittent fasting is an effective weight loss tool.

A 2014 study review concluded that this dietary regimen can cause weight loss of 3 to 8% over the course of 3 to 24 weeks, which is a significant amount compared to most other weight loss studies (15).

According to the same study, subjects also lost 4 to 7% in waist circumference, indicating a significant reduction in harmful abdominal fat that accumulates around the organs and can cause disease.

Another study showed that intermittent fasting causes less muscle loss than the standard method of continuous calorie restriction (16).

However, you should keep in mind that the main reason for the success is that you consume fewer calories overall with intermittent fasting. If you consume massive amounts of food during your eating phases, you are unlikely to lose weight.

Health benefits

Numerous studies have been conducted on humans and animals to investigate the effects of intermittent fasting. These studies have shown that intermittent fasting can have important benefits for weight management as well as body and brain health. It could even help you live longer.

Here are the main health benefits of intermittent fasting:

Weight loss: As mentioned above, intermittent fasting can help you lose weight and belly fat without having to consciously restrict calories (15, 17).
Insulin resistance: Intermittent fasting can reduce existing insulin resistance, lower blood sugar by 3 to 6% and reduce fasting insulin levels by 20 to 31%, which should help protect against type 2 diabetes (15).
Inflammation: Some studies have observed reductions in markers of inflammation, which are key factors in the development of many chronic diseases (18, 19, 20).
Heart health: Intermittent fasting can reduce levels of bad LDL cholesterol, blood lipids, inflammatory markers, blood sugar levels and insulin resistance, all of which are risk factors for heart disease (15, 21, 22)
Brain health: Intermittent fasting increases the levels of the hormone BDNF in the brain and could support the growth of new nerve cells. It could also protect against Alzheimer's disease (23, 24, 25, 26)
Anti-ageing: Intermittent fasting can extend lifespan in rats. Studies have shown that fasting rats lived 36 to 83% longer (27, 28).

Keep in mind that research in this area is still in its infancy. Many studies have been small or of short duration or have been conducted with animals. Many questions remain that need to be answered in future human studies (29).

Intermittent fasting makes a healthy lifestyle easier

Eating healthy is easy, but it can be damn hard to maintain over time. One of the biggest obstacles is all the work it takes to plan and prepare healthy meals. Intermittent fasting can make things easier because you don't have to plan and prepare as many meals as before. For this reason, intermittent fasting is very popular with life hack followers as it improves your health while making your life easier.

Who should avoid intermittent fasting?

Intermittent fasting is certainly not for everyone. If you are underweight or have a history of eating disorders, you should only do intermittent fasting with professional support, as this diet can otherwise prove harmful.

Should women fast?

There is some evidence that intermittent fasting may not be as beneficial for women as it is for men. For example, one study showed that it improved insulin sensitivity in men, but actually worsened blood glucose control in women (30).

Although many human studies are still lacking on this topic, studies conducted with rats concluded that intermittent fasting can make female rats emaciated, more masculine and infertile, as well as disrupt the female menstrual cycle (31, 32).

There are a number of anecdotal reports of women whose menstrual periods stopped after starting intermittent fasting and whose cycles returned to normal after resuming their previous diet.

For these reasons, women should be cautious about intermittent fasting. Women should follow other guidelines, such as transitioning to an intermittent fasting lifestyle more slowly and stopping immediately if they experience problems such as a missed period.

If you have fertility problems and/or are trying to conceive, you should consider giving up intermittent fasting. This diet is also a bad idea if you are pregnant or breastfeeding.

Safety and side effects

Hunger is the most common side effect of intermittent fasting. You may also feel weak and your brain may not be as efficient as you are used to. This may be temporary as it can take a while for your body to adjust to the new meal pattern.

If you have an existing medical condition, you should consult your doctor before starting this diet.

You should always consult a doctor before starting intermittent fasting if you:

Suffer from diabetes
Have problems with blood sugar regulation
Suffer from low blood pressure
Are taking medication
Are underweight
Have a history of eating disorders
Are a woman who wants to get pregnant
Are a woman with a history of irregular menstruation
Are pregnant or breastfeeding

Apart from this, intermittent fasting is considered exceptionally safe and harmless. There is nothing dangerous about not eating for a period of time if you are healthy and well nourished.

Frequently asked questions

Here are answers to the most frequently asked questions about intermittent fasting.

1. can I drink anything during the fasting phases?

Yes, water, coffee, tea and other calorie-free drinks are allowed. However, avoid sugar in your coffee. Small amounts of milk or cream may be okay.

Coffee can be particularly helpful during fasting as it can reduce hunger.

2. isn't it unhealthy to skip breakfast?

No. The problem is that most people who skip breakfast are living an unhealthy lifestyle. If you make sure that you eat healthy food during the rest of the day, then skipping breakfast is perfectly fine and not unhealthy in any way.

3. can I use supplements during fasting?

Yes, but you should bear in mind that some supplements, such as vitamin tablets, are better absorbed and/or work better with meals.

4. can I exercise while fasting?

Yes, fasting workouts are perfectly fine. Some people recommend taking branched-chain amino acids (BCAAs) before fasting workouts.

5. will fasting result in muscle loss?

All weight loss methods can cause muscle loss, which is why it is important to train with weights and maintain a high protein intake. In this context, one study showed that intermittent fasting resulted in less muscle loss than regular calorie restriction (16).

6. will fasting slow down my metabolism?

No, studies show that short-term fasting can actually increase the metabolic rate (13, 14). However, prolonged fasting that lasts longer than 3 days can reduce the metabolic rate (33).

7 Should children fast?

Allowing children to fast is probably a bad idea.

How to get started with intermittent fasting

Chances are you've done a lot of intermittent fasting in your life. If you've ever eaten dinner and then slept late and not eaten until lunch the next day, then you've probably already fasted for 16 hours or more. Some people instinctively eat this way. They are simply not hungry in the morning.

Many people see the 16/8 method as the simplest and easiest version of intermittent fasting to stick to in the long term, which is why it can make sense to start with this variant first.

If you find this form of intermittent fasting easy and feel good during the fast, then you can try moving on to a more advanced version such as 24 hours fasting once or twice a week (Eat-Stop-Eat) or the version where you only eat 500 to 600 kcal per day on 1 or 2 days per week (5:2).

Another approach is to simply fast when it's convenient for you, which means skipping meals from time to time when you're not hungry or don't have time to cook. There is no need to follow a structured intermittent fasting plan to reap at least some of the benefits.

Experiment with the different approaches and find something that works for you and fits in with your daily routine.

Should you try intermittent fasting?

Intermittent fasting is not something that everyone has to do. It's simply one of many nutritional strategies that can improve your health. Eating real food, exercising and getting a good night's sleep are still the most important factors to focus on.

If you don't like the idea of fasting, then you can simply ignore this article and get on with what works for you. At the end of the day, there is no universal, one-size-fits-all solution when it comes to nutrition. The best diet is the diet that you can maintain over the long term.

Intermittent fasting is great for some people and not for others. The only way to find out which group you belong to is to try this diet. If you feel good while fasting and you can imagine this diet as a longer-term nutritional approach, then intermittent fasting can be an effective tool for weight loss and improving your health.

References:

Source: https://www.healthline.com/nutrition/intermittent-fasting-guide

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