Home Healthy Eating Intermittent fasting: This is how intermittent fasting works

Intermittent fasting: This is how intermittent fasting works

by Josephine Andrews
Published: Last Updated on 176 views

Intermittent fasting, also known as intermittent fasting, alternates periods of fasting with days or hours when you are allowed to eat. You only consume calories in a fixed time window. The promised effects: Age-related diseases should be alleviated and losing weight and maintaining weight should be made easier. Find out here how intermittent fasting works and what it can actually do.

What is intermittent fasting?

The principle of intermittent fasting is very simple: there are phases in which you can eat normally and phases in which you don’t eat any calories. You can only drink plenty of unsweetened tea and water . The longest possible fasting period with this diet is 36 hours.

What does intermittent fasting mean?

Another name for intermittent fasting is intermittent fasting, which derives from the Latin word intermittere, which means “to interrupt” and “to suspend” in German.

Intermittent fasting is also called short-term fasting. There is no specific meal plan for this diet. In theory, everything is allowed during the eating phases. There is neither a requirement for certain foods nor for the calorie intake.

Ideally, however, you should prefer healthy foods. That means lots of vegetables, little refined sugar, no fast food, little meat, white flour, or white rice .

What happens to the body during intermittent fasting?

The principle of intermittent fasting is derived from the nutritional rhythm of our ancestors, the hunters and gatherers. They did not have a continuous supply of food and inevitably had to fast regularly. The human body is therefore used to fasting. Intermittent fasting should therefore also be practiced in the long term or permanently.

Since the fasting phases in intermittent fasting last a maximum of 36 hours, the body does not switch on its hunger program, in which it shuts down the metabolism. With common diets, this often becomes a problem, which is why a yo-yo effect quickly occurs.

This is how intermittent fasting works

How does intermittent fasting work? There is no single explanation or set of instructions for proper intermittent fasting. Rather, you can choose between different types of intermittent fasting. They differ according to the rhythm between the eating and fasting phases. It can be just a few hours or 1.5 days. You decide at what time you start and stop fasting.

Which variant you choose depends on your individual preferences and discipline in terms of food abstinence. For example, do you prefer to skip breakfast or dinner, or do you find it easy to go an entire day without eating?

The choice of the intermittent fasting variant affects the metabolism. If this has no energy sources available, it generates the sugar needed for the brain and other organs from the fat reserves. This process is called ketosis. The longer you fast, the more pronounced this process is.

It is important that you always drink enough – preferably water or unsweetened herbal teas.

Different intermittent fasting methods

There are different intermittent fasting times with the following rules:

Full fasting period

Fasting one to three days a week. There is then talk of 6:1, 5:2, 4:3 interval fasting. If you don’t last the whole day, you can eat up to 600 calories – but not in the form of carbohydrates, i.e. no pasta, no sweets, no alcohol. The individual fasting days should not follow each other.

36:12 rhythm

With this variant, you fast every other day. For one day you eat normally from 8 a.m. to 8 p.m., the following night and the entire following day you only eat liquids.

20:4 rhythm

There is only a four-hour window per day in which you are allowed to eat. For 20 hours there is nothing but tea and water.

16:8 rhythm

With this model suitable for everyday use, you fast for 16 hours and eat for eight hours every day. You can do this by skipping breakfast or dinner, for example. Slightly modified forms are the 18:6 or 15:9 methods.

Read more about 16:8 intermittent fasting here .


With this intermittent fasting variant, you are not allowed to eat anything for 14 hours and eat for the remaining 10 hours. Intermittent fasting 14:10 is said to be better for women, as their bodies fall back on their fat reserves after just 14 hours.

Women over 40 or 50 who are going through the menopause and are struggling with weight gain and belly fat like to use this variant.

The 14:10 is sometimes referred to as dinner cancellation .

Learn more about dinner cancellation here .

More intermittent fasting methods

There are other intermittent fasting models. The 12:12 variant is particularly aimed at beginners who initially find it difficult to go without food for a long time.

A very extreme form of intermittent fasting is 23:1. You are only allowed to eat something with her for one hour a day. In the USA there is talk of “One Meal a Day”. 23:1 is not suitable permanently. Only use this form for a few days at a time or once a week.

How long can you do intermittent fasting?

If you do not opt ​​for the extreme 23:1 intermittent fasting variant, you can use short-term fasting permanently and without a break. It is important that you eat a healthy and balanced diet during the eating phases. Also, drink a lot.

Beginners can slowly advance and start with the 14:10 or 16:8 method.

There’s nothing wrong with shifting the times slightly if it suits your everyday life better. One to two hours is no problem.

A so-called “cheat day” is also possible. If you have decided on the 36:12 rhythm or whole days of fasting, you can generally eat as you wish on the permitted eating days.

Breaking intermittent fasting for a weekend isn’t much of a problem either. However, this should remain the exception, otherwise the effect of intermittent fasting will be interrupted. Breaks often increase the dropout rate.

What is allowed in intermittent fasting?

Many people who start intermittent fasting are unsure of what is and isn’t allowed. We answer the most important questions for you.

  • What can I eat during intermittent fasting? In principle everything is allowed. There is no meal plan or grocery list. However, make sure you eat a balanced diet with lots of vitamins, minerals and fiber.
  • Can I eat sweets while intermittent fasting? Yes, this is also allowed in principle. However, it is not conducive to your health or weight loss. Sweet foods are often high in sugar and calories. Better to eat fruit.
  • What can I drink during intermittent fasting? It is best to drink water and unsweetened herbal teas. Ginger, cucumber, and lemon water are also allowed. Drinks containing sugar and alcohol are possible during mealtimes, but use them sparingly.
  • Can I drink coffee while intermittent fasting? This is not a problem during the eating phase. Black coffee is also possible during Lent. In the case of coffee with milk, the situation is different in this phase. Milk contains lactose, which affects blood sugar levels. Coffee with oat milk and almond milk, on the other hand, is allowed during intermittent fasting – but only in small amounts. Bulletproof coffee, i.e. coffee with butter and oil, is also in vogue. It can also be drunk during the fasting phase because it does not affect insulin levels and even stimulates fat burning .
  • Can I use artificial sweeteners during intermittent fasting? Artificial sweeteners such as aspartame are not recommended. They can trigger food cravings. Diet sodas are also better avoided. However, natural sugar substitutes such as stevia, xylitol and the like are metabolized without insulin and therefore have no effect on blood sugar.
  • Can you chew gum while intermittent fasting? Nothing speaks against chewing gum either. However, they increase the feeling of hunger in many people. Therefore, it is questionable whether chewing gum is beneficial during the fasting period.

Side effects of intermittent fasting

Intermittent fasting has disadvantages for the body. Fasting puts stress on the body. Anyone who is very stressed at work and in everyday life should refrain from intermittent fasting. This also applies to people with diabetes. On fasting days, there is a risk of low blood sugar (hypoglycemia).

Since the low calorie intake during the fasting phase leads to low blood sugar levels, headaches can occur. If these persist, you should check again whether the method you have chosen is good for you and possibly talk to a doctor about it. The latter also applies if you are taking medication.

Note that the lack of carbohydrates on fasting days can lead to bad breath – a side effect of ketosis. So drink a lot or suck on sugar-free candy.

People who skip breakfast should see if coffee on an empty stomach is good for them.

Women who are pregnant or breastfeeding should also not fast to ensure that the child receives enough energy and nutrients throughout the day.

If you are active in sports and would like to build muscle during intermittent fasting, you should consume enough calories and protein . If you pay attention to this, you can do intermittent fasting without any problems. Studies have even found positive effects on the release of human growth hormone (HGH). This affects muscle growth.

However, intermittent fasting can also be unhealthy if your diet is mainly high in sugar and fat. Since there are no recommendations for food, the German Society for Nutrition advises against it in order to reduce weight in the long term.

If you prefer white flour products, fast food and sweets during the eating phases, this can result in weight gain despite intermittent fasting. Then it seems as if intermittent fasting does not work.

effect of intermittent fasting

So far, most studies on intermittent fasting have only been carried out on experimental animals and proof in humans is still lacking. However, the available studies show that intermittent fasting probably increases life expectancy. However, there are no long-term studies on this yet.

Is intermittent fasting healthy?

Intermittent fasting uses the fact that so-called autophagy in the cells starts after 14 hours in calorie-free phases. The cells digest overaged and faulty building material, the body cleanses itself of contaminated sites. That could explain the sometimes amazing health effects of fasting.

Intermittent fasting may also prevent or improve various diseases. These include joint problems, cardiovascular diseases, diabetes and skin diseases such as neurodermatitis and acne. Fasting may even protect against various cancers.

Discussed benefits of intermittent fasting are further:

  • helps burn fat
  • inhibits inflammatory processes
  • reduces cholesterol levels
  • relieves chronic constipation
  • lowers blood pressure
  • stabilizes the blood sugar level
  • helps with irritable bowel syndrome with diarrhea and flatulence
  • can support the growth of new nerve cells (protection against Alzheimer’s disease)

If you have thyroid problems and suffer from Hashimoto’s thyroiditis, you can still do intermittent fasting.

Does Intermittent Fasting Help You Lose Weight?

Intermittent fasting is not a classic diet . However, it can help you lose weight if you eat a healthy, balanced diet and exercise regularly. It usually takes two to three weeks for the body to adapt and for the first results to show.

How much weight you lose varies – some people lose a pound a week, others two. It also depends on what you eat.

It is also possible for women to lose weight during menopause with intermittent fasting, but this is not a matter of course. You probably won’t lose the typical belly fat that way alone. The following also applies to them: Exercise and a healthy diet are basic requirements for the kilos to fall off.

Whether intermittent fasting can generally help against unhealthy belly fat is controversial. A more recent study with mice could not find any positive effect.

Who Shouldn’t Do Intermittent Fasting?

You should not do intermittent fasting if you

  • suffer from diabetes
  • have low blood pressure
  • take medications
  • be underweight
  • suffer from an eating disorder
  • are pregnant or breastfeeding
  • have to deal with menstrual disorders

Intermittent Fasting: Conclusion

Intermittent fasting is a type of fasting that can be easily integrated into everyday life and is also quite easy to maintain in comparison to longer fasting phases. The method is also suitable for changing your eating habits, losing weight or maintaining your weight.

But start with short fasting phases (16 hours) and listen carefully to yourself whether your current life situation (stress level) is a good time for intermittent fasting. If you can affirm this, are healthy, balanced and disciplined to a certain extent, there is nothing standing in the way of getting into this eating rhythm.

You may also like

Leave a Comment