Intermittent fasting kills your pounds: Almost no matter what else you eat - with interval fasting it's the rhythm that counts. You can find out here how this method works and whether it is suitable for you. In addition: the right diet for fasting plus a daily plan for the 16:8 variant.
Intermittent fasting is no longer just a trend, but is considered to be an all-purpose weapon in the fight to lose weight. It is supposed to boost fat burning and even have a rejuvenating effect.
Indeed: Studies show that intermittent fasting is particularly healthy - and puts all other diets in the shade.
How interval fasting works and what methods are available for intermittent fasting, you can find out here. We explain which concept is best for you and how much you can lose weight with which fasting method.
We have also put together a daily plan so that you know exactly what you can eat and drink.
What is interval fasting?
Intermittent fasting (lat. intermittere = interrupt, suspend) - also called interval fasting or part-time fasting - is not a fasting cure in the classical sense.
Instead, phases in which one eats normally alternate with phases of complete abstinence.
This way of eating should make it possible to benefit from the many advantages of fasting without feeling hungry or weak. For many, however, the main motivation is probably weight loss.
How interval fasting works
If you want to try interrupted fasting, there are three basic rules for you:
Find out which of the interval variations works best for you. Your choice depends on how long you can go without food. The different forms differ in the frequency and duration of the food restriction.
During the fasting phase only water or unsweetened drinks such as coffee or tea are allowed. During this time, the body draws everything it needs from your reserves.
During the rest of the time you may eat normally. Apart from the usual recommendations for a healthy diet - i.e. little refined sugar, not eating too much and too late, preferably no fast food - there are no guidelines.
Depending on individual goals and preferences, various forms of intermittent fasting are possible, which differ in their ratio of fasting time to eating time.
How long should I fast intermittently?
In contrast to therapeutic fasting or detoxification, fasting is not only practised for a certain period of time, but can be applied daily.
If you can cope well with interval fasting, you can practice it for the rest of your life. It is also not important to adhere strictly to the prescribed times every day.
You will also feel the positive effects if you intermittently fast three out of seven days a week, for example.
To get in, you can start with a few days a week. And don't worry: your body is prepared to not eat for a long time.
But the more often you manage it, the better it is for your health - and also for the success of your diet.
The different methods of interval fasting
16 to 8, 10 in 2, 5 to 2 - interval fasting may sound complicated at first.
Behind these terms, however, there are no complicated calculation formulas, but rather the different methods that exist for interval fasting.
Whole days fasting according to the 5:2 method
The British nutrition expert Michelle Harvie developed the 5:2 concept with her colleague Tony Howell at the University Hospital of South Manchester.
Eat what you feel like on five days - and fast on two days, with a small amount of food allowed. Women are allowed to eat up to 500 kcal, men up to 600 kcal, for example in the form of vegetables, fruit or soup.
This allows you to make the fasting days quite pleasant. The choice of fasting days is also arbitrary, but they should not follow each other. You can, for example, take part in a birthday party or go out for a meal. It is important to drink enough, but always calorie-free, preferably water and tea.
Plus points: The 5:2 diet is suitable for everyday use and flexible. The fasting days can be kept up well, because you don't have to give up completely. After the diet phase you simply switch to just one fasting day and can thus keep your weight well.
Caution: Not suitable for children, pregnant women, competitive athletes, people with an eating disorder or underweight. Ask your doctor if you have diabetes or other chronic diseases.
Suitable for: People who find calorie counting too laborious, but who find it easy not to eat. No guidelines on carbohydrates or fats. Regulates the blood values.
Weight loss factor: 500 to 800 g per day of fasting are included.
16:8 - 8 hours eating, 16 hours fasting
The most popular form of interval fasting at present is the 16:8 method, five kilos less is always possible. Interval fasting at 16:8 is based on "time-restricted feeding". This means that the time span of the food intake in the daily interval is limited.
In each 24-hour interval you may eat within an 8-hour period, but not in the remaining 16 hours. This means that you have to schedule your meals differently. Normally, you would eat dinner at about 8 p.m., and maybe have breakfast again at 7 a.m.
With the 16:8 principle, you try to extend the meal break to 16 hours. That means: eat dinner earlier and have breakfast later. Three healthy, balanced meals are recommended.
During the eight hours you are allowed to eat what you want, but you don't have to hold back anything. However, it is clear that it makes no sense to eat food that is constantly rich in fat and sugar.
If you are very disciplined, try not to snack between your meals: this way you can build in small fasting intervals again.
By the way: The more severe form of 16:8 is the 20:4 variant - also called Warrior diet. This extreme variant is not suitable for beginners and is only suitable for a short time.
Plus points: With 16:8 you can choose the period of fasting to suit you. If dinner is celebrated in your family, it makes more sense to postpone breakfast. This makes the method suitable for everyday use.
Caution: pregnant women, nursing mothers, children and people with eating disorders should not do interval fasting according to the 16:8 method.
Suitable for: All those who prefer to look at the clock rather than count calories. Good for beginners, as they do not need to fast for whole days or longer. Ideal for working people.
Weight loss factor: 1 to 2 kg per week are possible.
6:1 - eat for 6 days, fast for 1 day
The California-based journalist and author Jane Kennedy is the inventor of the One-Day Diet. Her main topics are health, naturopathy and wellness.
This method involves fasting on only one day per week. On this day the focus is on plenty of fluids (at least three litres) and fat burner drinks.
About: 1 teaspoon of apple vinegar and 1 teaspoon of honey in a glass of water. Or: the juice of half a lemon in a glass of water. The drinks dampen hunger and stimulate the metabolism. Also permitted are diluted juices, whey and fat-free broth. Coffee, alcohol and calorie-containing drinks must be avoided.
On the remaining six days of the week you eat as usual - of course as varied and calorie-conscious as possible. It is recommended not to eat anything heavy the evening before the fasting day. So the body can get in the mood for the diet day.
10 in 2 - 1 day eating, 1 day fasting
First you have to understand this: 10 (spoken "one zero") in 2 means one day eating (1) and one day fasting (0) within 2 days. The method is also known as alternating fasting, meaning eating and fasting alternately.
This variation was invented by the Austrian cabaret artist and psychologist Bernhard Ludwig. Motto: "Get and stay slim with pleasure". He has lost over 20 kilos with this method, the book to his recipe for success: Tomorrow I may eat what I want.
This is how it works: you fast every other day. The food intake on Eating Day normally takes place over a period of twelve hours. This is followed by 36 hours in which you do not eat anything. This way the body is only deprived of nutrients for a short time. On Eating Day, anything you like is allowed.
Plus points: Alternating fasting is the most effective way to save calories.
Caution: You should be quite fit for frequent fasting. There is no yo-yo effect, but it does challenge the body more than the gentler fasting methods.
Suitable for: People with fasting experience who wish to lose weight over a long period of time.
Losing weight factor: 2 to 2.5 kg per week should at least at the beginning fall.
Dinner Cancelling - eat during the day, fast in the evening
The good old Dinner Cancelling can be regarded as a forerunner to interval fasting. Current studies show that it is particularly sensible not to eat anything after 4 p.m.
This is related to the circadian rhythm - day and night determine the metabolism. Thus it comes that with test persons the same food causes a smaller rise of the blood sugar mirror in the morning than in the evening.
As the name suggests, you should skip dinner when cancelling dinner. You can increase the effect if there are as many hours as possible between the last meal of the day and the next, i.e. breakfast.
During this time, you may consume calorie-free drinks such as water and unsweetened tea. However, you should avoid coffee in the evening, as it can have a negative effect on your sleep rhythm. When you have breakfast the next morning, make sure that you don't put in the calories you saved in the evening.
Plus points: Skipping dinner once or twice a week - you can do that! Always remember that fat burning works better overnight than during the day. This ensures good success with only small cuts in your habits. Side effect: You gain time to do something for yourself, your sleep becomes calmer.
Caution: Not so ideal for those who eat together in the family in the evening. A glass of hot water or herbal tea will help with night-time cravings.
Suitable for: Lent novices, cooking addicts, singles.
Weight loss factor: The scale can show up to 500 g less in the morning.
Interval fasting is so healthy
Countless reports speak for themselves: Interval fasting seems to work. But, what is the scientific study situation? Is it really as healthy as is always claimed?
Indeed, various studies have shown that a slightly reduced calorie intake leads to a higher life expectancy and can prevent or improve many diseases.
For example, experiments with mice that were specifically exposed to eating breaks have shown improvements in blood counts and a reduced likelihood of diabetes, cancer or heart disease due to a slight calorie deficit.
In another study, interval fasting even had life-prolonging effects. Whether the results can be transferred to humans, however, could not be scientifically shown so far.
And also what concerns removing, past analyses permit a positive conclusion. An analysis from the year 2015 comes to the conclusion that interval chamfered represents a valid possibility of the energy restriction regarding weight acceptance, fat mass and blood sugar regulation.
Another study also proved that interval fasting is superior to a diet that continuously reduces calories and carbohydrates. Subjects showed a greater reduction in body fat and improved insulin sensitivity.
Opponents of the popular 16:8 method hold against it: 16 hours are much too short to create a ketogenic metabolic situation in the body as with therapeutic fasting - i.e. to switch to fat burning instead of glucose storage.
For the organism, especially for the heart, the concentrated food intake alternating with pseudofasting may even be extremely stressful, and the hormone balance may also be disturbed by a too large fasting window.
Ernährungswissenschaftliche evaluation by the DGE
The German Society for Nutrition points out that there are only a few human studies available to date that prove the effects of interval fasting. The many different forms of fasting and the different study participants (e.g. normal-weighty or overweight people) make the evaluation even more difficult. There are currently no studies on the long-term effects of fasting.
Nevertheless, the DGE emphasizes that the previous data indicate that intermittent chamfering has a positive effect on health and weight loss.
Dangers and side effects
There are no specific dangers with interval fasting. Side effects of intermittent fasting can be fatigue or headaches. If you experience these symptoms, it is best to consult a doctor to find out whether and how you should practice one of the fasting methods.
This also applies if you suffer from pre-existing conditions such as diabetes or low blood pressure, or if you are very underweight.
It is also important with interval fasting that you eat a healthy and balanced diet during the phases when eating is allowed.
If you consume fewer calories than usual during the fasting period, it is all the more important that these calories come from nutrient-rich foods and provide you with all the nutrients you need.
For whom is interval fasting suitable?
For many people, the method can be an interesting approach to losing body fat without prohibiting certain foods or keeping the current body weight despite some feasting.
It may be easier than following a diet, but for many people it is simply not possible to eat at all for one or two days a week, or not to eat for 16 hours every day - with the certainty that they will not have to give up anything the next day.
Among sporty people, eating in 16:8 time is particularly popular. They build their sport into the fasting phase in the morning and then add energy at midday. Not just to lose weight, but because it works well.
A late breakfast and/or an early dinner is feasible for many people. In return they can save themselves the calorie counting and the demonising of carbohydrates or fats.
Moreover, intermittent fasting is particularly suitable for office and everyday life and requires almost no planning or previous knowledge.
A further advantage of the part-time fasting method should be that you learn again to distinguish between real hunger and appetite. If you don't eat for a longer period of time, hunger usually disappears by itself - because the body usually has enough reserves to compensate for some missing meals.
If you want to lose a few pounds quickly without giving up your favourite dish, you can succeed with this method.
However, a more constant calorie intake may be more sensible due to the individual sports workload or occupational stress. Part-time fasting and losing weight is therefore not the best option for everyone.
Nutrition during interval fasting: You can eat and drink
With interval fasting there are no guidelines as to what should be eaten or drunk. That means: salad and curry are okay - but doner and coke as well?
The DGE criticizes that many concepts of interval fasting give no, or only very vague, recommendations as to what exactly should be eaten during intermittent fasting. Often there is no change in diet at all when beginners start interval fasting.
So if you continue to eat unhealthy food, you may lose weight - but that is not healthy.
In order to get the maximum benefits from interval fasting, there is no way around a balanced diet. This means: two to three large meals a day, which provide you with satiating proteins, healthy fats, energy-giving carbohydrates and vital substances.
A porridge, muesli with fruit or an omelette with vegetables and avocado are suitable for breakfast. Lunch and dinner should consist mainly of vegetables and vegetable protein sources, for example legumes, soya or pseudo-cereals. Sweets, red meat, trans fats and alcohol should be avoided as far as possible.
Green vegetables such as broccoli, spinach or pak choi contain only a few calories, but they are rich in vitamins, minerals and secondary plant compounds.
Fruit should not be missing either, for example strawberries, blueberries, bananas or apples.
Good fats from avocados, salmon, olives or seeds and nuts give you the energy you need throughout the day.
For the last meal before and the first meal after the fasting phase we recommend a purely vegetable diet, as it is alkaline-forming and supports the body in breaking down undesirable substances.
What can I drink during the fasting phase?
No matter which fasting method you have chosen for yourself: it is important that you drink enough, especially during the fasting phase. In this way you support fat burning and cell regeneration.
Still water or unsweetened herbal or fruit tea is best. Milk, soft drinks, sugared iced teas or other energy drinks are taboo.
Coffee is perfectly okay - but only black. Latte macchiato and capuccino unfortunately do not count as they contain milk.
Can I drink alcohol?
Alcohol is allowed during interval fasting, but only during the meal window and in moderation. If you drink alcohol during Lent, you break the fast.
Daily schedule: Recipes for intermittent fasting
For the most popular variant, the 16:8 method, we have compiled an example day.
According to expert Dr. Petra Bracht, MD, the ideal eating window is between 12 noon and 8 pm. However, many people do not manage to organise an early dinner because of their working hours - they can push breakfast further back.
Tip: If you want to start with interval fasting, it is best to try it out on the weekend. With an early dinner, a late brunch and enough sleep in between, it's relatively easy to get to 16 hours of fasting.