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Intermittent Fasting — What It Is and How It Works

Intermittent Fasting — What It Is and How It Works

Intermittent fasting is one of the easiest ways to improve your health and lose weight sustainably. The best thing about it is that you can maintain your weight without falling victim to the yo-yo effect. With intermittent fasting, you don't have to give up your favourite foods; you simply eat at certain meal times. Intermittent fasting helps to prevent or even significantly improve lifestyle diseases such as diabetes 2. [1]

Blog Author Jris Health Coach at CARE
Jris Bernet

Health Coach EN

Published in Nutrition
13 min read · Feb 28, 2024

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What Is Intermittent Fasting?

Intermittent fasting is very easy to apply. The 24-hour day is divided into two phases: a fasting phase and an eating phase. You decide when you eat your first meal of the day and when you eat your last meal. In between, plan two to a maximum of three meals and as few snacks as possible.

The shorter your meal times and the longer your fasting period, the more effective intermittent fasting will be.

What Is Allowed During Intermittent Fasting?

If you want to lose a lot of weight or improve your health because you have poor blood values, then it's worth rethinking your eating habits and giving up foods like pizza and fried foods during intermittent fasting. If you are metabolically healthy and only have a few kilos too many on your ribs, then you don't actually have to give up on certain foods. What and how much you can eat depends entirely on your health and your energy consumption. The only thing that applies to everyone: the fresher and unprocessed the food, the better.

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Does chewing gum help with fasting?

During fasting, you should not eat anything naturally, but what about chewing gum? Opinions differ here. For some, chewing gum helps to curb the desire for sweets. Others quickly get hungry again due to the stimulated flow of saliva. Keep in mind that there are also artificial sweeteners in chewing gum, which don't do your gut any good.

If it helps you, then chew gum every now and then to support your fasting efforts. Otherwise, it's better not to.

Calorie-free Drinks During Fasting

You can drink the following during the fasting phase:

  • Plenty of water, preferably flavoured with herbs such as peppermint or basil and a slice of lemon
  • Black, unsweetened coffee or bulletproof coffee
  • Herbal tea, black tea, matcha - all unsweetened

Healthy Eating During the Eating Phase

During the eating phase, you can theoretically eat whatever you want. You will benefit health-wise during your fasting period, but if you actually have health problems or want to improve your health and wellness, then it is worth paying attention to your meals during intermittent fasting.

Stick to a few simple guidelines when planning healthy meals during intermittent fasting:

  • Lots of fresh vegetables and salads
  • Pulses, sprouts and seeds
  • Ethically-sourced and organic meat, as well as poultry, eggs, etc.
  • Fish - sustainably farmed
  • Reduce foods with a high carbohydrate content such as pasta, potatoes or bread - rarely as a main meal, but rather as a side dish
  • replace dairy products with plant-based alternatives here and there, and always keep an eye on the sugar content
  • Pay attention to healthy fats: Olive oil, olives, tree nut oil, nuts, avocado oil, avocados, hemp oil, hemp seeds ...
  • Do not eat fruit as a snack but as a dessert
  • As rarely as possible: Deep-fried and highly processed foods
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Is Snacking Allowed During the Eating Phase?

It is best and easiest to stick to two meals during intermittent fasting. Every time you eat something, your blood sugar level rises, and your digestion gets extra work.

If you can't avoid snacks, keep something healthy, like nuts, olives, a piece of cheese, vegetable sticks, or a protein shake, handy.

Can I Take Food Supplements During Intermittent Fasting?

In contrast to prolonged therapeutic fasting, intermittent fasting does not deprive you of any nutrients. However, if you do have deficiencies, you can cover these with the appropriate food supplements.

Magnesium, zinc, vitamin D3, and omega-3 fatty acids are also recommended during intermittent fasting.

But be careful: Zinc, for example, can cause nausea on an empty stomach. Ask CARE to test you for deficiencies so that you know which food supplements are right for you.

What Health Effects Does Intermittent Fasting Have?

As with all fasting methods, intermittent fasting also triggers various physical processes that have positive effects on your health.

Regular intermittent fasting:

  • has a blood sugar-regulating effect (HbA1c improves)
  • can minimize chronic inflammation
  • can have a pain-relieving effect
  • lowers blood pressure
  • strengthens the immune system
  • boosts the fat metabolism
  • helps you lose weight
  • simplifies weight control
  • promotes mindfulness and the ability to concentrate
  • Can protect against neurodegenerative diseases

Digesting food requires a lot of energy and physical resources. During the fasting period, you relieve your organs, and when the body's own fat oxidizes (you lose weight), you can detoxify a little at the same time. In a nutshell, regular intermittent fasting definitely has positive effects on your health. [1,2,3,4,5]

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Autophagy — Your Personal Recycling

One of the most important discoveries in connection with fasting is certainly autophagy. The Japanese scientist Yoshinori Ohsumi was awarded the Nobel Prize for this in 2016. At the same time, fasting, especially intermittent fasting, has become increasingly popular. Autophagy literally means "eating yourself". It means that defective or broken proteins and cell organelles "digest" themselves and are thus taken out of circulation or reassembled.

The process is comparable to a recycling plant. The cell waste is sorted, and what can still be used is recycled and reused. The remaining waste is disposed of so that it cannot cause any damage if it is left lying around for any length of time. By eliminating the damaged cell material, fewer pathological cells can multiply and form tumours. Invaders such as viruses and bacteria can also be combated more quickly in the cells.

Therefore, autophagy is a central key point in infections and diseases. It is generally assumed that autophagy sets in after 12 to 16 hours of fasting. [6,7]

Can You Lose Weight Healthily With Intermittent Fasting?

Intermittent fasting is not a diet; you don't have to give up certain foods. Still, if you want to lose weight sustainably and healthily, you should definitely question your eating habits and plan a healthy diet based on fresh, preferably unprocessed foods in your daily routine to achieve the possibly best results.

If you start intermittent fasting, you will automatically eat a little less because you cannot snack during the long fasting phase. Longer fasting phases lead to fat burning, and for many people, this is a completely new, improved body sensation. This motivates you to question your eating habits.

This creates a desire to eat more healthily, which in turn has a positive effect on fat burning. Whether you can lose weight with intermittent fasting is also a matter of mind. It is no longer stressful for you as soon as your body gets used to only eating within a certain time frame. You won't get ravenous hunger attacks, your metabolism will become more flexible, and you can extend your fasting windows a little. This also makes losing weight easier.

Nevertheless, you should bear a few things in mind, which we will dive into below.

From Carbohydrate Metabolism to Fat Metabolism

Even if you can theoretically lose weight with intermittent fasting, it doesn't happen on its own. Even with just one meal a day, you can eat more than your body actually consumes. The "unused" energy intake ends up as fat on your hips.

Intermittent fasting on its own is generally not enough to lose weight if someone overeats; it also requires a certain adjustment to your diet and calorie intake. And don't forget to exercise!

In order to start burning fat, your glycogen stores must first be emptied. This means that when you consume carbohydrates with your food, some of the sugar is made available as energy and stored as glycogen in the liver and muscles. The less full your glycogen stores are, the faster fat (your body fat) is converted into energy. Then you are actually burning fat, and you are actually losing weight.

Let's assume your last meal shortly before 7 pm consists of a fennel salad as an appetizer and a cauliflower curry with chicken breast for the main course. This gives you a very low carbohydrate intake, even if you eat large portions. The next morning, you skip breakfast and plan your lunch for around 1 pm. This means you have fasted for 18 hours. Your glycogen stores have been empty for a while and your fat-burning is running at full speed - you are losing weight.

Things look different if you eat hummus with flatbread as an appetizer shortly before 7 p.m. and pasta as your main course, accompanied by two glasses of red wine. This not only fills your glycogen stores, you'll also have some left-overs for your waist if you are not super sporty after the meal.

Additionally, your liver has to break down the alcohol before it can move on to other tasks. As a result, your sleep will probably not be as good. Poor sleep, in turn, affects your hunger and satiety hormones, ghrelin and leptin. You'll probably be hungrier than usual the next morning and perhaps a little cranky, too. You are looking forward to your lunch at 1pm, and your choice of food will again tend to be more carbohydrate oriented and fatty.

After 18 hours of fasting, you've just managed to start burning fat—or maybe not. Therefore, weight loss is unlikely to succeed despite intermittent fasting.

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Counting Calories or Eating Intuitively?

Counting calories is out. Everyone talks about listening to your body and feeling how much and what you should eat. That sounds great and is certainly easy to do for young, sporty people who need an incredible amount of calories. For everyone else, this is a big challenge. “A calorie is not a calorie” and it makes a big difference which foods make up the calories.

Nevertheless, it is helpful to know your personal calorie needs (approximately), especially if you want to lose weight but are not succeeding. Your calorie needs are calculated from your basal metabolic rate and your energy expenditure.

Your basal metabolic rate is the energy you need without doing anything. Your breathing, heartbeat, digestion, brain, and organs need quite a lot of energy just to keep you alive. Your basal metabolic rate depends on your age, gender, height, and weight. The taller, leaner, and more muscular you are, the higher your basal metabolic rate and the higher your calorie intake.

On the other hand, your energy expenditure is the additional energy you need to work or during sports - in other words, during your activities. It is calculated using the PAL value (Physical Activity Level).

If you now know how many calories are available to you each day, the easiest way to do this is to use an app to track them. After a few weeks, you will be familiar with the macros, carbohydrates, fats, and protein and know which meals contain how many calories. In addition, your eye for portion size will be trained, and you will soon be able to estimate your own meals and forget about counting calories again.

Among other things, calorie counting has fallen into disrepute because many people have become so obsessed with it that it has taken on pathological traits and even contributed to eating disorders. This is, of course, not good. The aim is to spend as little time as possible on food and to eat intuitively. But our lives and our lifestyles have unfortunately developed in a different direction, and most people need time and knowledge to be able to eat intuitively in the long term.

As a CARE member, you can have your body composition measured regularly. Together with your Health Coach, you can calculate your metabolic rate and, thus, manage your total calorie intake. Your Health Coach will support and guide you if you want to start interval fasting or lose weight in a targeted and healthy way.

Does Exercise Help You Lose Weight During Intermittent Fasting?

A lot of muscle mass is definitely helpful during intermittent fasting. The more muscle you have, the easier it is to start burning fat with intermittent fasting if you reduce the amount of carbohydrates a little. But intermittent fasting combined with exercise also helps you to lose weight and, above all, to get a defined body. [8]

Muscle training is not for everyone; men usually find it a little easier. Nevertheless, women should get to grips with the subject from age 40 at the latest and move away from the cross-trainer and towards the dumbbell section. Alternatively, there is EMS training (electro-myo-stimulation (myo comes from the Greek and means muscle)) or Aurum, which advertises targeted strength building with just 6 minutes of training time.

Fear of the Yo-yo Effect or Muscle Loss During Fasting?

As mentioned, intermittent fasting is not a diet - it is a lifestyle measure you can do every day or a few times a week. This regularity prevents the typical yo-yo effect that occurs after a diet. This is another reason why you can lose weight healthily and sustainably with intermittent fasting. You can decide for yourself how much you want to lose and at what point you only want to maintain your weight. This can be regulated less by intermittent fasting and more by your energy requirements, i.e. the amount of calories you take in relation to your consumption.

Athletic men, in particular, are afraid of losing muscle through fasting. There are still too few studies to be able to answer this question conclusively. But there is every indication that muscle loss is kept within very narrow limits and that there is no significant muscle loss, especially in the long term. In the case of fasting beginners who are not yet metabolically flexible, i.e. who do not burn fat so quickly, some protein from the muscles is initially used to generate energy. [9]

On the one hand, a balanced diet that contains sufficient protein and, on the other, exercise and strength training to build and maintain muscle are important. However, this is important with and without intermittent fasting and especially for women.

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What Intermittent Fasting Schedules Are There?

The great thing about intermittent fasting is the many different methods and intermittent fasting schedules that can be used. If you are a beginner to fasting, then try extending the natural night fast a little—perhaps to 12 to 14 hours. If you do this well, you can extend the fast to 16 hours. Give yourself enough time—you don't have to become an expert in intermittent fasting within a week!

Intermittent Fast 16:8

The 16:8 fasting schedule is the most popular and easiest for most people. After 16 hours of fasting, by skipping breakfast, you only eat your lunch. You plan your dinner within the next eight hours.

Dinner Cancelling

Dinner Canceling is almost the same concept, except you skip dinner and eat breakfast and lunch instead. This method can actually be quite successful, as digestion is already complete when you go to bed. This is beneficial for the quality of your sleep as well as for many regeneration and build-up processes.

Unfortunately, dinner cancelling is not so easy, as eating always has a social component.

The 18:6 or even 20:4 method is the same as the 16:8 method but has a few more health benefits, as the fasting state lasts longer.

OMAD - One Meal A Day

OMAD (One Meal A Day) is a 23:1 fasting schedule. Some people appreciate this method, especially during stressful times at work, as they can keep a clear head during the long fasting period. From a nutritional point of view, the OMAD method is not a problem in between meals but is not recommended in the long term.

But why? Getting enough nutrients with just one meal a day is very difficult. Even with a 20:4 it is likely difficult. Many people also overeat excessively when there is only so little time and one meal to eat.

The 5:2 Method

Like OMAD, the 5:2 method is more suitable for advanced fasta. You eat normally five days a week, and on two (non-consecutive) days, you reduce your calorie count to 500 to a maximum of 700.

There is likely an intermittent fasting schedule that will suit you and your rhythm of life. Try it out and practise it until you feel comfortable with it. It is then advisable to introduce other fasting schedules. This will make you more and more flexible and less dependent on certain eating times and habits.

Intermittent fasting is easy to integrate into everyday life and is a good introduction to the world of fasting. In addition to intermittent fasting, there are some other exciting fasting methods that can benefit your health.

List of References

Blog Author Jris Health Coach at CARE

Jris Bernet

Health Coach EN at CARE Zurich

About the author

Jris is a health coach (nerd) and blog author at CARE. She has many years of experience as a coach for classic lifestyle conditions such as diabetes and women's health. She enjoys facilitating health challenges and courses. Fasting, keto, sleep, women's health and biohacking - Jris feels at home in these topics. When she's not working for CARE, she loves to listen to health podcasts and try out new (health) gadgets. Her credo: "It's never too late to start living a new lifestyle."