Fast? Or do you prefer a diet?
Fasting and diet – hotly debated topics – but what’s the difference?
Both terms come from very different contexts and you should not confuse them as synonyms.
Fasting means voluntarily giving up solid food and luxury foods for a limited period of time. It has existed in various forms of application for thousands of years, often anchored in religions such as the fasting month of Ramadan in Islam or the Christian fasting period before Easter. Fasting is a break and addresses the unity of body, soul and spirit, at least that’s what the founders of classic fasting say. While abstaining from food for about two to three weeks, the focus is on adequate hydrationabout tea, water, broth and a balance of rest and physical activity in your everyday life. Fasting is still trendy these days! Regardless of whether therapeutic fasting, water fasting or intermittent fasting: In our part of the world, it is a big movement and could offer some people an opportunity to start a change in diet , but it is not an option for pure weight loss.
A diet, on the other hand, is not a time-limited phase of fasting. Much more it means a long-term healthy lifestyle:Overweight, with the exception of actual physical or mental illnesses, is mostly due to an unhealthy diet and insufficient exercise in everyday life. Ultimately, the weight gain results from excessive calorie intake per day. If the supplied energy is greater than the consumption, the body stores the excess energy in the form of fat deposits for “bad times”.
Your daily menu plays an important role in the diet: if you eat a balanced diet, but you supply your body with less energy than it needs, you will permanently lose weight. It’s not about simply eating less, but about eating the right thing, in other words: wholesome and healthy. Vegetables, fruits, high quality protein and high quality carbohydrates are ideal for this.
You have to differentiate this from the so-called “crash diets” , which are usually fad diets. They cannot help you either for permanent weight loss or for a balanced everyday life. With these trend diets, you limit your food to the bare essentials, which creates a yo-yo effect after the end of the dietcan almost never be prevented. Really just a short crash for your body, unfortunately without any positive consequences.
What happens to your metabolism while fasting?
The conversion of your organism during fasting takes place in stages. Your body is switched to “nutrition from within”. This means that the substances required for metabolism come from the body itself. The breakdown of the body’s own substances is called catabolism. The counterpart is anabolism. Body structures, e.g. B. built up muscle but also fat tissue. If you neither lose weight nor gain weight, both mechanisms are usually in balance.
If the energy supply is restricted, the body changes its metabolism: your basal metabolic rate falls, your metabolism slows down – the focus in fasting is on the energy supply of your most important body functions. Your adrenal gland pours out more adrenaline.Heart rate, temperature, blood pressure and blood sugar level drop ; a similar extreme example in the animal world is hibernation.
The energy you need for fasting is provided by three sources: carbohydrates in the form of the body’s own glycogen, proteins mainly from your muscles and fats from the subcutaneous fatty tissue. Two biochemical processes take place in
hunger metabolism in order to generate energy. The body needs gluconeogenesis right at the beginning of the fast
your sugar stores up. The storage unit for carbohydrates is called glucose or glycogen when it comes to chains of glucose. The liver, kidneys and muscles provide you with short-term glycogen reserves. After a day, however, these memories are already exhausted. You excrete more water, which is why the weight loss is greater at the beginning of the fast.
After these short-term reserves have been mobilized, protein breakdown takes place temporarily . Your metabolism mainly relies on muscle proteins, but also on superfluous structural protein and defective enzymes in your digestive tract.
A protein-saving mechanism then arises during the course of the fastas shown in the figure below. The protein loss can initially be 75 mg / day, but with longer periods of fasting the breakdown is reduced to around 20 mg / day.
As a by-product of protein breakdown, uric acid and ammonia rise in the blood, which should be checked regularly.
After about 5 to 7 days, your fat reserves are needed for energy production. The triglycerides from the subcutaneous fat tissue – that is, your fat deposits – will from now on be broken down mainly for the function of your organs. About ketogenesis is your metabolism from fatty acids of the triglycerides ketone bodies ago. These are very high-energy compounds that are used by some cell types, such as red blood cells (erythrocytes) and cells in your brain, to provide energy.
During the reduced food intake, there is a certain hunger adaptation , i.e. an adaptation to the lack of nutrients. In the long term, however, such a food deficit would lead to deficiency diseases and ultimately death.
What Does Science Say About Fasting?
Researching fasting opens up a wealth of websites that promise health benefits. But the more difficult question is what the scientific basis of such therapies looks like.
So far, there are almost no conclusive findings from large-scale studies for humans. Only experiments on animal models allow an indication of possible positive effects.
The German Obesity Society (DAG) rejects fasting. The possible side effects such as cardiac arrhythmias, vitamin and mineral deficiency and insomnia are too risky, especially for older and multimorbid people. Your body runs an emergency program, which is not physiologically understandable or justifiable. There is often talk of cleaning up waste products in the intestines. Scientifically speaking, such a slag does not exist. This could mean breakdown products of the organism, which are actually generated and normally excreted via your kidneys and liver. However, these are permanently removed from your body – even without you fasting.
The therapeutic fasting according to Buchinger was investigated somewhat better, and a study was published in 2019. The study evaluated data from patients who fasted for 7 to 14 days. According to studies, parameters relevant to your metabolism such as blood pressure and insulin level are reduced by not eating (Goldhamer et al., 2002; Schmidt et al., 2010; Michalsen et al., 2013).
Metabolic diseasessuch as metabolic syndrome, hyperlipidemia, type 2 diabetes mellitus and gout, i.e. pathological symptoms that can be influenced by your own eating habits, also show improvements under fasting therapy. They also include cardiovascular and chronic inflammatory diseases of a rheumatic nature (osteoarthritis, ankylosing spondylitis) as well as intestinal diseases (Crohn’s disease, ulcerative colitis) and other pain disorders (fibromyalgia, migraine). Fasting for allergies, psychosomatic illnesses and depression has been shown to have healing effects(De Toledo et al., 2002). A disadvantage of the research is that the fasting patient groups were not compared with other patient groups who did not fast or who followed a different controlled diet.
Intermittent fasting in particular is currently a much studied form of therapy.
Results from animal studies suggest that avoiding food regularly could lower your risk of developing chronic diseases. In addition, intermittent fasting shows life-prolonging effects in animal experiments.
There are no human studies that prove the effect of intermittent fastingHowever, there is now some research on intermittent fasting in humans. Some of the results are contradicting, but it wasn’t until the beginning of December 2019 that a study appeared in which patients with metabolic syndrome who were already being treated with statins and antihypertensive drugs intermittently fasted for 12 weeks (fasting 14 hours per day). The participants could choose for themselves during what time of day they ate. After the study period, the patients’ cardiometabolic health improved. The authors conclude that intermittent fasting is a potentially powerful lifestyle intervention that can complement standard medical treatment for metabolic syndrome.
A study on this subject is currently being carried out at the University of Graz: the Inter-FAST study. Under the direction of Prof. Frank Madeo, 90 participants will not only study the potential effects of fasting on humans, but also examine the associated molecular and physiological changes.
Madeo assumes that the so-called autophagy, an independent breakdown process of your cells, will maintain your state of health. This is based on the assumption that intermittent fasting destroys cell damage, DNA mutations and defective enzymes
Fasting: Healthy or Unhealthy?
Currently, the study situation on fasting is still too unexplored to be able to make any clear statements. Although fasting is generally considered to be health-promoting, there is no project in the world that systematically examines the effects of fasting on humans in a medical and molecular-biological manner.
If you are interested in fasting anyway, it is best to discuss with your doctor whether and to what extent it is suitable for you.