What is fasting?
Fasting is one of the oldest practices in the world and has been used for thousands of years for health and religious reasons. Meanwhile, giving up food at certain times has become a new health trend. There are different types of fasting, from short-term calorie restriction (12-24 hours) to longer fasts. But all types have one thing in common: the body is deprived of food for long enough to change its metabolism. Instead of burning glucose to feed cells, the body burns fat to produce ketones. This changes the biochemical functioning of our cells.
Many dietary and nutritional trends of the past have focused on what one should eat. So-called therapeutic fasting, for example, allows only liquids such as tea, vegetable broth or diluted juices for a certain period of time, while alkaline fasting allows only fruit and vegetables.
Intermittent fasting: Consciously abstaining from food at certain times
Intermittent fasting (also known as interval fasting) focuses less on what you eat and more on WHEN you should eat. It involves taking in calories in shorter, well-defined periods of time. The basic premise of intermittent fasting is to limit food intake to a specific period of time and to avoid eating outside that period while maintaining adequate nutrient levels. In reality, those who practise intermittent fasting can eat whatever they want, within reason. It is not necessary to give up anything, but eating must be done in moderation and with a specific purpose.
Different methods of intermittent fasting:
The best-known form of intermittent fasting is the 16:8 version. This allows you to eat over an eight-hour period before fasting for the remaining 16 hours. In practice, your daily schedule might look like this: breakfast at 8 a.m., lunch around 12 p.m. then the last meal of the day at 4 p.m. The important thing to remember is to have the last meal at least eight hours before midnight.This is a gentle form of losing weight without having to give up certain foods. Other advantages: only fat is lost, not muscle mass. This variant is relatively easy to integrate into daily life and avoids the well-known yo-yo effect and hunger pangs. However, to achieve long-term success, the necessary discipline and the right timing are important.
Other possible rhythms are 18:6 and 20:4, which involve fasting for 18 or 20 hours respectively. However, you do not have to eat three meals a day, you could have two or even just one. A version without dinner, also known as “dinner canceling”, is another particularly effective option. Breakfast is the one meal you should never skip.
Another popular fasting method consists of eating normally for five days a week, with only a small amount of food allowed on the remaining two days. The rule is that women are not allowed to eat more than 500 calories a day and men no more than 600. The advantage of this method is that it is relatively suitable for everyday use and no significant sacrifices need to be made. Studies have shown that this method reduces hypertension and improves cholesterol levels. But be careful: even if small indulgences are allowed on normal days, one should not feast endlessly. A healthy, balanced diet is essential! Another disadvantage is that on fasting days you have to be able to consume very few calories, which can be quite a challenge. This method is not recommended for people with previous illnesses. It is important to follow a fasting day with at least one day in which you eat, to avoid hunger stress.
Basically, this method works similarly to the 5:2 method, but with Eat-Stop-Eat you fast for 24 hours (no longer) two days a week (no longer). Unlike the other methods, no calorie consumption is allowed on fasting days, but drinks such as water, unsweetened tea and black coffee can be consumed. It is believed that every 24 hours of fasting allows a weight loss of between 0.65 and 3 kg.
ADF – Alternate day fasting (ADF):
Another intermittent fasting method is to have one fast day a week when you do not eat any solid food. Alternate day fasting (ADF) – where you fast for a day, eat the next, and so on – is also popular and effective. Another key point of this is that you only eat three meals a day (breakfast, lunch and dinner) on non-fast days, with no snacking in between.
The health benefits of fasting
Unlike for our ancestors, today eating is more than just an elementary requirement in order to satisfy hunger: enjoyment is the focus of mealtimes shared with family or friends, but we also (all too) often treat ourselves to a piece of chocolate as a reward or a bag of crisps when we are stressed. We are also quick to grab a snack without a second thought whenever we are even the slightest bit hungry. Because, let’s be honest, when was the last time your stomach genuinely “rumbled”?
“We are eating ourselves to death”, as Russian doctor Galina Shatalova wrote in her book of the same name. And in fact, excessive eating and poor diet and lifestyle have caused or increased the risk of many civilization diseases, including cardiovascular disease, diabetes, cancer and many more. Even a slightly high BMI (body mass index) can cause one of these diseases. The best preventative measure is regular fasting periods of at least 16 hours. This results in a number of health benefits that are scientifically proven.
So why do you need a break from eating of around 16 hours in intermittent fasting? Because it takes this long to trigger what is known as autophagy, the body’s internal purification process. This has lots of positive benefits for health and the human body, as the self-cleaning process takes all of the “rubbish” that food brings into our body and recycles some of it. Cells are repaired, oxidative stress is reduced and inflammation is reduced. This also reduces the risk of cancer. However, this important regeneration phase only kicks in after 16 hours of fasting. In addition, during breaks between meals you can only drink unsweetened drinks such as water, black coffee with no sugar, or green tea. Even a sip of fruit juice will disrupt the process!
In a nutshell, the fasting phase is part of the body’s own detox program and purifies all of the body’s cells, with beneficial effects for many organs and chronic diseases. Autophagy also has an impact on the aging process, so fasting is a real fountain of youth – provided that half of the fasting time, i.e. the first eight hours, are before midnight.
This information about autophagy was only discovered relatively recently, primarily thanks to the work of Japanese cell biologist Yoshinori Ohsumi, winning him the 2016 Nobel Prize in Medicine.
Weight loss is probably one of the most common reasons why interval fasting is so popular. People who follow this type of diet lose weight faster and tend to keep it off for longer, provided they follow it. Intermittent fasting increases the body’s ability to utilise energy from stored fat reserves, thus promoting fat burning. It actually increases the secretion of HGH, a hormone involved in fat loss, muscle growth and rejuvenation. Since you can eat practically anything, you do not experience the undesirable yo-yo effect that many diets entail. Furthermore: intermittent fasting specifically attacks abdominal fat. So-called visceral fat may become chronically inflamed over time and actively interfere with metabolism.
Intermittent fasting improves insulin sensitivity, which reduces blood sugar levels and the risk of developing diabetes. Studies show that even short periods of calorie restriction change the composition of the gut microbiome, with a clear predominance of beneficial bacteria. These bacteria in turn produce hormones that communicate with the brain, supporting metabolism at the cellular level. Research also suggests that interval fasting slows the accumulation of fat in the pancreas, which fuels insulin production. This increases the risk of developing diabetes.
Intermittent fasting also has a positive effect on heart health, as it reduces cholesterol levels, lowering the risk of developing heart disease. Blood pressure and already elevated blood fat levels can also be normalised by fasting, studies show. Furthermore, limited food intake is believed to slow down the ageing of blood vessels and reduce the risk of atherosclerosis.
Finally, the brain can also benefit from intermittent fasting. Studies show positive effects especially on long-term memory. For example, researchers have found that intermittent fasting is associated with the development of new neurons in the adult hippocampus, which may help slow down age-related cognitive decline in adults.
Another benefit of fasting is its positive impact on the aging process, slowing it down. For example, studies have shown that irregular mealtimes and eating late mean that the skin takes longer to regenerate or “repair” any damage. Do your skin a big favor and skip the evening feasting!
Animal testing has also shown that regular fasting of at least 16 hours can reduce the aging process by a third. Interestingly, skipping dinner had a significantly more positive effect than leaving out breakfast, even if still fasting for 16 hours.
Many people who fast regularly feel more active, capable and content – and not just because they are getting closer to their target weight as each day passes. Fasting also triggers a biochemical reaction that affects our psyche, because 16 hours of mostly overnight fasting increases the concentration of the happiness hormone serotonin. This is thanks to what are known as ketones, which are produced when the body breaks down surplus energy reserves. These ketone bodies also stimulate nerve cells and distribute increased amounts of neurotransmitters such as serotonin early in the morning.