- What is intermittent fasting?
- How does intermittent fasting work?
- The most popular methods of intermittent fasting?
- How to lose weight with intermittent fasting
- Combining exercise with intermittent fasting
- Building muscle with intermittent fasting
- The Leangains method
- Veggie and vegan intermittent fasting
- What is the difference between intermittent fasting and therapeutic fasting?
- Can I lose weight with therapeutic fasting?
- Frequently Asked Questions
What is intermittent fasting?
Intermittent fasting is the little sibling of therapeutic fasting, which has been well-known since the 1970s.
While fasting describes an uninterrupted period of time in which you eat nothing at all, intermittent fasting (from the Latin intermittere – to interrupt) can be defined as a pattern of eating in which repeated, short periods of abstinence from food are alternated with periods of “normal” eating. It is usually characterised by fasts of 16 – 24 hours at a time or, alternatively, periods of eating with a heavily reduced calorie intake (depending on the method).
Intermittent fasting is known for its simplicity and flexibility and is therefore usually easier to implement than many other well-established diets. It is particularly ideal for people who lead busy lives because it makes everyday meal-planning a lot easier.
Is intermittent fasting healthy?
Overall, it is safe to assume that intermittent fasting is largely risk-free for healthy people. Most benefit from structuring their diet this way and attest to increased energy and resilience.
However, it can lead – especially in the beginning, when the body is still adapting to the adjustment – to side effects, although these usually subside quickly:
- Fatigue can increase significantly in the evenings but this can be a positive, because it leads to better sleep.
- Right at the beginning, dizziness and headaches can occur. We advise staying well hydrated to prevent this.
- In the first few days, food cravings and mood changes can arise, but these quickly disappear as soon as the body becomes accustomed to the new diet.
- For pregnant and breastfeeding women, as well as people suffering from an eating disorder, intermittent fasting is not an option.
- In the case of chronic illness a trusted doctor should be consulted first.
How does intermittent fasting work?
During intermittent fasting, you switch from a period of normal eating to a period of no food intake at all. The total lack of food during the fast naturally leads to an overall reduced calorie intake and thus has great potential to deliver weight loss results.
One of the great promises of intermittent fasting is the “cleansing” effect it is said to have in the body. Prolonged periods without solid food are likely to thank for this. Autophagy (the body’s process of recycling damaged cells) sets in after about 12 hours without energy intake and is the foundation for the numerous health benefits of fasting. Cells that have already been damaged are either renewed or destroyed by the body. It is important to note that this process can only occur when the body is no longer engaged in digestive processes.
In this way, intermittent fasting promotes weight loss and reduces the risk of some diseases, such as cancer or dementia. Animal testing has also demonstrated further benefits, including a longer life expectancy, healthier blood pressure and a lower incidence of age-related diseases, along with a lower susceptibility to bacterial infections.
A large proportion of findings from animal testing cannot be directly applied to humans, but they can often indicate a trend.
Today’s ubiquitous excess supply of food makes us less resilient.
The frequent switch between periods of low or no food availability and phases of sufficient food supply, which characterised the daily life of our early ancestors, is beneficial for our health and boosts our resilience overall.
Where can you go wrong with intermittent fasting? Your guide to intermittent fasting.
There is really very little you can do wrong. However, it wouldn’t do any harm take a look at the following tips and tricks for a brief how-to on intermittent fasting. If you take note of these few points, nothing can stand in your way!
- Take it easy: make changes to your diet in gradual steps
If you find it difficult at first, your stomach is relentlessly rumbling, and you’re having trouble falling asleep, increase the number of hours you go without food slowly but steadily.
- Listen to your nutritional instinct and find your own routine
Find out what routine you like best. Don’t want to skip breakfast? Start your eating phase in the morning and begin your fast in the afternoon. Prefer dinner? Skip your morning meal and start fasting late in the evening, after dinner.
- Concentrate on what is good for you
Your body is not a machine. Give it enough time to come to terms with the change. You will soon adapt completely and feel great in no time!
- Avoid stress as much as possible
In order to give your body the chance to adapt, you should, especially during periods of fasting, allow yourself to rest. So try not to subject yourself to unnecessary stress.
- Eating a healthy and balanced diet is essential
Even if intermittent fasting is relatively flexible, you should of course not spend your free-eating period consuming junk food and soft drinks endlessly. Upfit’s personalised meal plans for intermittent fasting can help you maintain a healthy and balanced diet. Don’t forget to drink plenty of water. Unsweetened tea and black coffee are also permitted during fasts.
- Don’t let exceptions drive you crazy
Once in a while, you might decide to go out for that dinner with your friends or break your fast earlier in the day because you’re feeling particularly hungry. Don’t panic. Exceptions – as long as they remain exceptions – will not block the path to your dream figure.
The most popular methods of intermittent fasting
There are several different approaches to the structure of intermittent fasting. We introduce you to the three most popular methods: alternate-day fasting (ADF), the 16:8 diet and the 5:2 diet. They may seem complex at first, but once understood, they are relatively easy to put into practice.
All methods at a glance
|5:2 Diet|| |
|16:8 Diet|| |
Alternate-Day Fasting (ADF)
Probably the most well-known form of intermittent fasting, alternate-day fasting, is an alternation between one day of normal eating and one day of eating nothing at all. During the fasting day, only water, unsweetened tea and coffee are allowed.
|1||Only water, coffee, tea without sugar||Eat and drink as desired||Only water, coffee, tea without sugar||Eat and drink as desired||Only water, coffee, tea without sugar||Eat and drink as desired||Only water, coffee, tea without sugar|
|2||Eat and drink as desired||Only water, coffee, tea without sugar||Eat and drink as desired||Only water, coffee, tea without sugar||Eat and drink as desired||Only water, coffee, tea without sugar||Eat and drink as desired|
Who is ADF suitable for?
- ADF is feasible for anyone with good health and self-discipline.
- This diet is mainly for people who want to lose weight.
- It is especially suitable for those who like exercising and want to lose body fat, but are not focused on building muscle.
- The ADF diet is very practicable for people who lack self-discipline, as postponing or swapping phases around is not possible.
If you still have trouble finding the motivation to make changes, take a look at our Motivation Guide to get some valuable and helpful tips.
Is there anything to bear in mind about ADF?
ADF should allow you to shed those pounds without having to worry too much. If you also choose to avoid sugary foods during the eating phases and make sure you eat a lot of vegetables and high-quality protein (e.g. lean meat), the process will be accelerated and you will lose less muscle mass. Another way to maintain muscle mass and still reap the benefits of fasting is to have 3 protein shakes on each fasting day (each consisting of about 30g of protein powder in 300ml of water – preferably vegan protein like rice, pea or hemp in any flavour you like). An unbalanced diet with lots of carbohydrates (bread, pasta, potatoes, etc.) and few vegetables is not recommended.
Deficiencies can quickly arise due to a low intake of important micronutrients, such as vitamins and minerals. Ultimately, fasting is not a substitute for a healthy diet. The Upfit Nutrition Guide for Healthy Eating can tell you all about how to eat a healthy diet.
The 5:2 Diet
The 5:2 diet does not involve a proper fasting period. Instead, each week is divided into 5 days when you can eat normally and 2 days on each of which women can eat a maximum of 500 kcal and men 600 kcal. These calories should be spread out over one or two small meals of vegetables and protein.
|Eat and drink as desired||500 kcal (women), or 600 kcal (men)||Eat and drink as desired||500 kcal (women), or 600 kcal (men)||Eat and drink as desired||500 kcal (women), or 600 kcal (men)||Eat and drink as desired|
Who is the 5:2 diet suitable for?
- This diet can be practised by anyone with good health and self-discipline.
- If you’re struggling with the idea of not eating for a whole day and are a serial snacker, 5:2 is for you.
- You should set yourself fixed “fasting” days for every week (e.g. Monday and Thursday), so that this new way of eating becomes habitual.
- Don’t betray yourself and your goals – there are no official guidelines on what you should eat, but be sensible!
- The 5:2 diet is ideal if you want to do a lot of intensive exercise during the 5 eating days.
- It is also suitable for the long term and can be implemented as a permanent change.
Is there anything to bear in mind about the 5:2 diet?
The 5:2 diet is a fairly flexible variation of intermittent fasting that promotes weight loss and allows for intensive exercise. However, this can only really be successful under a few conditions: firstly, it is advisable to have your “fasting” days on the same days of each week, and secondly, the diet on the “normal” days should also be adjusted to include lots of vegetables, lean protein sources and little sugar. When it comes to exercise, it makes sense to use the fasting days as rest days.
When done correctly, this method of intermittent fasting offers you the opportunity to lose weight for good without losing muscle mass.
Reports on the 5:2 diet show that reducing the amount of calories on fasting days is more difficult for many than not eating altogether. Reports of torturous cravings are not uncommon. It is all the more important to cover your permitted calories with foods with a low energy density (salad, vegetables, some lean meat) and to drink a lot.
The 16:8 Diet
The 16:8 diet does not work on a day-to-day basis, but on an hour-to-hour basis instead: each day, you can eat normally within an 8 hour period, while for the remaining 16 hours you are only allowed water, coffee and unsweetened tea. At first glance, this seems to be a very easy pattern to implement, since the time you are asleep counts towards the total fasting time for each day. Typically, eating times are between 8 a.m. and 4 p.m. (where dinner is omitted), 10 a.m. and 6 p.m. (compressed day), or 12 p.m. and 8 p.m. (where breakfast is omitted).
You can therefore adjust the start and end of the eating phase flexibly according to your eating habits and daily routine. But beware: since it is important to get used to this new habit, the 16/8 method should be thoroughly stuck to – even on weekends and public holidays. For many, this can be a problem, because spontaneity is also severely restricted.
Sample days (treat all 7 days of the week the same)
|Before 8 a.m.||Sleep, only water, coffee and tea without sugar||8 a.m. to 4 p.m.||Eat and drink as desired||After 4 p.m.||Sleep, only water, coffee and tea without sugar|
|Before 10 a.m.||Sleep, only water, coffee and tea without sugar||10 a.m. to 6 p.m.||Eat and drink as desired||After 6 p.m.||Sleep, only water, coffee and tea without sugar|
|Before 12 p.m.||Sleep, only water, coffee and tea without sugar||12 p.m. to 8 p.m.||Eat and drink as desired||After 8 p.m.||Sleep, only water, coffee and tea without sugar|
In contrast to the other two methods presented, the calorie intake hardly changes during the free meal times. However, the long break between the eating phases definitely delivers results if you want to achieve and maintain your ideal weight and good health. Of course, even with the positive effects of intermittent fasting, you will be treading water if you only eat junk food and sweets.
A healthy diet is non-negotiable for a healthy body.
Who is the 16:8 diet suitable for?
- This type of diet is also feasible for anyone who is healthy and self-disciplined.
- The 16:8 method is particularly suitable for those who are better able to cope with small but regular changes and prefer to have a permanent routine.
- People who have an inconsistent sleep schedule or travel a lot/for long periods of time will have problems.
- People who have trouble resisting small snacks in addition to large meals will celebrate good success with this method.
- However, people who are used to eating many small meals throughout the day will find it difficult to cope with the small time constraint.
Is there anything to bear in mind about the 16:8 diet?
You can leave most of the organisation to Upfit – we’ll create your perfectly tailored meal plan and save you a lot of time. By taking your individual preferences into account, we can help make intermittent fasting work for you.
Once you’ve reached the weight you were aiming for, a few exceptions to the 16:8 structure can be made now and again, as long as they’re rare. In terms of both exercise and mental well-being (e.g. struggling with hunger or perseverance), there are no limitations to this method, which is why it is absolutely suitable for long-term nutrition.
How to lose weight with intermittent fasting – Key tips
Is weight loss your goal? Intermittent fasting has proven itself as an effective method time and again, and many people have already had success with it. Because of its effects on the body, intermittent fasting is primarily used as a tool to achieve an ideal weight. Switching to intermittent fasting is very easy to do as there are few restrictions during “eating times”. The fact that it works for most people despite this makes it an exciting approach to losing weight (and subsequently maintaining your new, lower weight).
Avoiding certain dishes while fasting automatically reduces your calorie intake. In this way, the number of calories you burn outweighs the calories you require to maintain your current weight, and thus leads to weight loss.
If you want to learn more about how many calories you need per day, feel free to use our calorie calculator.
Which meal should I skip when doing intermittent fasting?
It is recommended that most skip breakfast and start with lunch as their first meal of the day. If you then consistently leave your daily carbohydrate intake until dinner time, your leptin level throughout the entire day should increase, as studies have shown. Leptin is the hormone responsible for feeling full, so this allows you to avoid those pesky hunger pangs. With leptin’s help, it is very easy to maintain this diet permanently, especially if you want to lose weight first. The phase of heightened fat burning, which occurs after about 10 – 13 hours of fasting, remains unaffected by the lack of hunger.
Furthermore, when carried out correctly, you should not fall victim to the dreaded yo-yo effect after your desired weight loss has been accomplished, since your metabolism will not shut down and muscles are not broken down.
If you are striving for weight loss, but don’t want to give up certain foods and enjoy following a routine, you will achieve your goals with intermittent fasting. Upfit’s personalised meal plans can make all of this possible for you! We are more than happy to help if you want to slim down with intermittent fasting.
Combining exercise with intermittent fasting
Intermittent fasting involves going without food for extended periods of time, which can raise concerns about not being able to perform at 100%. Are these concerns justified?
Does intermittent fasting affect my performance?
Are you worried that after abstaining from food for a while, your physical performance will suffer? Are you afraid that you won’t be able to push yourself as much? Studies have shown that these fears are unfounded. Physical strength and performance during the fasting phase have proven to be no lower than during phases of food intake. In fact, after about 10-12 hours without eating, the energy that you require for exercise is mainly taken from your fat reserves!
Fat burning is heightened during fasting periods.
What is the perfect exercise schedule for intermittent fasting?
According to studies, it makes no difference at what time and during which fasting period you exercise. Just tune into your body and determine when your workouts fit best into your everyday life, because there is no perfect exercise schedule. Intermittent fasting should make life easier by reducing unnecessary burdens.
Building muscle with intermittent fasting
If your goal is muscle hypertrophy instead of weight loss, achieving it can be a bit more difficult with intermittent fasting methods. Intermittent fasting automatically reduces your calorie intake – after all, you go without energy for long periods of time, energy that is essential for building muscle. Fasting not only lowers your energy intake; it also alters how hungry you feel and other relevant hormonal processes. Thus, trying to create the calorie surplus required for muscle building with high-energy foods can pose a difficult challenge.
On the positive side, however, is the fact that, during the fasting phase, the body “falls back” on its fat reserves as an energy source. Soon after a workout, it should then receive the nutrients and energy that it needs to recover. It is usually advisable to leave your workout until the end of your fasting period and then to break your intermittent fast with the meal you eat after you train. Thus, the 16:8 diet can, in fact, be used with a few modifications in order to build lean mass effectively.
The Leangains Method
The pioneer of this permanent form of nutrition, which simultaneously allows constant gain of lean muscle mass and loss of body fat is the Leangains founder Martin Berkhan, who has developed a total of 4 quite similar approaches with different focuses for this purpose. Berkhan himself is a good example of how well his method works, although there are now many who have got into excellent shape following his example.
Berkhan’s approach combines the temporal component of the 16:8 diet with a kind of “carb cycling”, i.e. a different distribution of macronutrients on workout days and rest days.
Of course, a well structured strength workout, performed at least 3 times a week, is essential if you want to progress with this method.
The idea behind this is to utilise the positive effect of carbohydrates on muscle hypertrophy on workout days and to keep insulin levels as low as possible on non-workout days by eating a low-carb diet in order to shift the body’s main energy source to fats. If you are looking for some inspiration for your low-carb diet, browse through our Low-Carb Guide. This results in an alternation of build-up and break-down phases in which the body breaks down more fat than it builds up due to the coordinated stimuli of nutrition and training, but at the same time builds up more muscles than it breaks down.
The Leangains Method is without a doubt a fascinating approach. However, it requires a lot of time and planning, as you need to adjust the distribution of carbs and fats differently on workout and rest days.
Veggie and vegan intermittent fasting
Are you vegetarian or vegan but still like the idea of intermittent fasting? Are you, however, afraid that it won’t work for you because you are concerned that symptoms of deficiency could arise? If yes, Upfit is definitely the right place to be! We will tailor your Intermittent Fasting Meal Plan to your personal preferences and eating habits with the utmost consideration. You can rely on us to take care of all those essential nutrients!
Most people are unaware that fasting was originally a religious tradition. Nowadays, there are various types of fasting. For example, it can be carried out voluntarily under the supervision of professionals over a limited period of time (so-called “therapeutic fasting”), where the aim is usually to achieve health-boosting results. Nevertheless, fasting is unfortunately often associated with starvation or used as a form of crash diet without professional supervision. Did you know, for example, that fasting alone does not result in permanent weight loss, but practising it consistently can indeed help you change your eating habits for good?
Therapeutic fasting is the best-known type of traditional fasting and enjoys recurring popularity. To help prevent incorrect execution, we’ll tell you more about the most effective approaches to therapeutic fasting as well as the medical and psychological benefits.
The most famous form of fasting: therapeutic fasting
Therapeutic fasting, which is now carried out in clinics under medical supervision, is an invention of the German doctor Otto Buchinger (1878-1966). In addition to the support they provide during the dietary transformation, trained staff also encourage patients to engage in leisure activities. The focus is not only on food, but also on enriching pursuits such as music, reading, meditation and experiencing nature. Buchinger therefore also referred to therapeutic fasting as the diet of the soul, since periods of abstinence from food have been shown to benefit both the entire body and your mental well-being.
How does therapeutic fasting work?
The day before the actual therapeutic fasting begins, the patient’s calorie intake is lowered to about 1000 calories. Caffeine, alcohol and nicotine should no longer be consumed from this point onwards (at the latest). On this day, you should start preparing yourself mentally for the time ahead, get sufficient exercise and try to avoid stress. The intestine is then emptied with the help of enemas.
After the preparation day, the usual duration of a course of therapeutic fasting is 7-10 days. However, the length depends on various factors and is initially prescribed by specialist personnel. Shorter fasts can boost motivation and perseverance, especially for people who are healthy but would like to be in tune with their body and soul again. Certain clinical pictures also benefit from a shorter as opposed to a longer, exhausting course of treatment. In some cases, the optimal fasting period can last up to six weeks.
At the end of the therapeutic fasting treatment, at least three extra days should be left free to allow yourself to return to normality and, if necessary, to adapt to a healthy diet. When breaking the fast, you should gradually reintroduce solid, yet light food – ideally fruit and vegetables – into your diet. You should avoid shovelling your food down and instead eat consciously. Patients should make sure to drink enough fluids. The table below shows how many calories you should consume over the course of each day.
|Day after therapeutic fasting||Recommended calorie intake|
What can I eat while fasting?
According to Buchinger, solid foods should be avoided during therapeutic fasting. Unsweetened tea and water are allowed. Juice and vegetable broth can also be consumed in moderation. You don’t have to worry about any of this, however, as trained staff at the clinic will take care of everything during the fasting phase.
What are the benefits of therapeutic fasting?
In recent years, more and more medical benefits of therapeutic fasting have been discovered for a long, diverse list of diseases. As a result of the changes that occur in the metabolism and hormone balance during the fast, psychological improvements have also been observed. In addition to a general increase in mental well-being, many rave about increased concentration. One reason for this may be the cells’ improved ability to regenerate, which develops due to the lack of new building materials in the body (which usually come from food). The body thus relearns how to use its existing resources.
Therapeutic fasting in the treatment of disease
Today, therapeutic fasting is used primarily to treat specific diseases. The current research demonstrates multiple health benefits for diseases and other conditions such as arthritis, migraines, arthrosis, diabetes and chronic inflammation. It is therefore likely that therapeutic fasting benefits the metabolic system as well as psychosomatic and pain-related conditions. Nonetheless, it should be kept in mind that in most studies a change of diet was also implemented after the end of the therapeutic fasting period, which could be responsible for the positive changes.
Can anyone try therapeutic fasting?
Are there any disadvantages to therapeutic fasting?
Especially at the beginning, side effects from therapeutic fasting can occur, but these usually subside quite quickly. Since the body first has to adapt to the new circumstances, the following side effects can, but won’t necessarily, occur:
- Circulatory problems
- Changes to sleeping pattern
- Muscle cramps
- Low blood sugar level
- Electrolyte imbalances
- Back pain
What is the difference between intermittent fasting and therapeutic fasting?
You’ve heard a lot about both terms so far and are now probably wondering how intermittent fasting and therapeutic fasting differ from one another. We have summarised the most important aspects for you in a table below:
|Intermittent fasting||Therapeutic fasting|
|Permanent change in diet||Short-term diet|
|No supervision||Care in a specialised clinic|
|Healthy, balanced diet||Complete abstinence from food|
|No rules – it doesn’t matter what you eat||Rules that must be followed|
Intermittent fasting is intended as a stand-alone dietary change that can be planned and carried out at home for the foreseeable future. Therapeutic fasting, on the other hand, is supervised over a limited period of time. The important difference is that therapeutic fasting is carried out in specialised clinics with trained staff. You will be supported by experts the entire time, offered further opportunities such as meditation or psychotherapy and you are able to share your experiences in group discussions. Unlike intermittent fasting, you should not attempt therapeutic fasting by yourself.
Can I lose weight with therapeutic fasting?
It is important to note that therapeutic fasting should not be used as a weight loss measure. It is used to achieve medical and psychological improvements. Although the focus is health improvement and not weight loss (despite the total absence of food), weight loss is a guaranteed bonus of therapeutic fasting.
Intermittent fasting, in contrast to therapeutic fasting, can serve as the first steps to a long-term dietary transformation. This means that your desired weight loss can be implemented in a healthy way and, what’s more, actually be sustained in the long term. In many cases, the restricted periods of food intake automatically lead to a reduction in calories and thus to weight loss without causing major hunger-related problems. However, due to the lack of hard and fast rules, there is no guarantee of successful weight loss.
Want to lose weight or achieve another goal with the 16:8 method? Then Upfit is the perfect place for you!
Frequently Asked Questions
How healthy is intermittent fasting?
Intermittent fasting is beneficial to health in many ways. For one thing, calorie restriction, achieved naturally through intermittent fasting, is scientifically the biggest contributor to a lengthy lifespan. In addition, the fasting periods establish improved cell regeneration throughout the body and relieve our digestive system. This relief leads to improved immune function and greater overall well-being.
Fasting AND stimulating metabolism: is it safe?
Metabolism and digestion are two separate things. Our metabolism is constantly active and is mainly stimulated by physical activity. In this respect, intermittent fasting won’t do any harm to your metabolism.
Is it possible to build muscle with intermittent fasting?
With the right distribution, volume and timing of your macronutrient intake, you can indeed build muscle during intermittent fasting. Gains won’t appear as quickly as they do in a bodybuilder’s “bulking” phase, but you avoid gaining a large amount of body fat at the same time, which bodybuilders have to make an effort to lose again (in the “cutting” phase) after they’ve finished bulking.
What happens if I do eat something during the fasting period?
Intermittent fasting fulfils two functions: first, it serves to prevent too many calories from being consumed and thus to regulate weight, and second, it triggers the process of autophagy, in which the body boosts cell regeneration instead of forming new cells. Both of these functions promote better health. If you eat or drink something low in calories during the fasting period, the influence on your weight will be negligible. In all likelihood, however, autophagy will be paused completely, since it only sets in after a certain length of time during which the body has received no food whatsoever.
- Anson R. M., Jones B., de Cabod R. (2005): ‘The diet restriction paradigm: a brief review of the effects of every-other-day feeding’. In Age, 27, pp. 17–25.
- Dohm, G. L., Beeker, R. T., Israel, R. G., Tapscott, E. B. (1985): ‘Metabolic responses to exercise after fasting’. In J Appl Physiol, 61 (4), pp. 1363–1368.
- Zimmet, P., Thomas, C. R. (2003): ‘Genotype, obesity and cardiovascular disease – has technical and social advancement outstripped evolution?’. In J Intern Med., 254, pp. 114–125.