WHAT ARE THE FASTING METHOD MOST POPULAR ？FASTING VARIANTS:FROM THE LIMITATION OF MEALS TO THE COMPLETE DEPRIVATION OF FOOD.
We will present below four forms of fasting, the most common today, with their advantages and disadvantages. We will also describe the functioning and the good practice of these forms of fasting, and we will be based on recent scientific publications.
What is certain is that all living things, and therefore all human beings, are prepared to adjust to the state of fasting. However, we were not prepared for the food glut resulting from the Neolithic agricultural revolution.
Fasting has been shown to promote health as well as longevity and reduce the risk factors for the diseases most responsible for death and loss of autonomy in Western society:
• Metabolic syndromes
• Type 2 diabetes
• Cardiovascular illnesses
• Neurodegenerative diseases [1, 2]
In addition, fasting promotes cell renewal by stimulating autophagy  and stem cell production .
The concept of fasting we are talking about here is a nutritional intervention that triggers metabolic changes in the body that occur in the absence of food and cause deficiencies. It is a modification of the metabolism (MMD) which goes into “young” mode. In general, the form of food which allows this shift of the metabolism to a fasting state is greatly reduced in calories.
What you will learn
INTERVAL FASTING:IMPOSE A TIME LIMITATION FOR YOUR MEALS.
This form of fasting involves limiting meal times during the day. So each day the body has a certain amount of time during which it is in a state of fasting. Typically, an 8 hour window is chosen every 24 hours (8/16 fast).
Human studies have shown that limiting meal times is also effective in the prevention and treatment of obesity, as well as metabolic disorders such as type 2 diabetes. This is due, among other things, to reducing daily calorie intake .
Contrary to the widely held view that breakfast is the most important meal of the day, recent studies have shown that omitting breakfast for adults is not only harmless , but can even be beneficial to health . It is also important to use the hours of daylight for food, as the metabolism is most active during daylight hours and probably especially in the morning .
• No prolonged food deprivation.
• No deliberate reduction in calories is necessary, as this usually happens unconsciously due to reduced meal times.
• Easy for those who don’t like breakfast or find it easy to skip the evening meal.
• Difficult to respect for those who find it difficult to do without breakfast or supper.
• This type of fasting loses the benefits of prolonged fasting, such as the activation of autophagy or the production of stem cells.
PUT INTO PRACTICE :
The principle is simple: you can eat for the first eight hours, then fast for sixteen hours. In order not to “suffer” too much from this long period of fasting, it is best to start the fast after dinner and continue until lunch. This way, you keep two important meals: lunch and dinner. Thus, you can provide your body with all the nutrients it needs.
Intermittent fasting has become the most common type of fasting. This type of fasting is based on alternating between periods of deprivation of 24 to 48 hours and normal periods of meals.
The most popular type of intermittent fasting is the one mediated by Michael Mosley : the 5: 2 diet which proposes to fast two non-consecutive days each week. This technique is mainly inspired by the results of two research groups: that of Michelle Harvie, who studied the effect of two consecutive days of fasting each week ; and that of Krista Varady who studied the effect of alternating-day fasting for a total of three days of fasting per week .
These results show the equivalence and also the superiority  (in particular with regard to the increase in insulin sensitivity ), of intermittent fasting compared to continuous calorie restriction for losing weight, maintaining weight loss, increase insulin sensitivity, and improve other health indicators.
• Meal preparation on the fast days of the 5: 2 diet requires an understanding of the caloric values and glycemic load of the foods consumed, which positively affects food choices on non-fast days.
• The two non-consecutive – or even consecutive – days of weekly fasting can be chosen freely, thus facilitating the organization of daily life.
• With one or two days of fasting, the MMJ does not involve the preponderant use of fats (as would be shown by the presence in the blood of the products of their degradation, called ketones), which testifies to a partial benefit of the fast. (without activation of autophagy and stem cell production).
• Added to this is the fact that the first day of fasting is when the body creates stress signals (adrenaline, cortisone). Therefore, it is to exert a lot of effort for little gain .
• Limiting the amount of food consumed leads to a decrease in the intake of essential nutrients such as vitamins, minerals, antioxidants, lipids and essential amino acids. The use of a good quality vitamin and omega-3 supplement is recommended or at least considered for fasting longer than 24 hours, keeping in mind that the general diet should be based on natural foods, fresh and rich in micronutrients.
PUT INTO PRACTICE
Intermittent fasting results in a reduction in calorie intake for one or two days. Mosley suggests limiting calorie intake for two non-consecutive days each week (500 kcal for women and 600 kcal for men) and eating normally for the other five days. There are many disclosure publications to better understand how to prepare for the diet every day and during fasting days we recommend The Longevity Diet by Valter Longo  and The 5: 2 fast diet by Michael Mosley .
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This is the most traditional form of fasting which involves the absorption of only water (or a very limited amount of food) over a period of three or more consecutive days (up to 21 days) [16 ]. Several publications demonstrate the effectiveness of this approach , for example in the treatment:
• Rheumatoid arthritis 
• Cardiovascular diseases 
• Metabolic syndromes 
• Type 2 diabetes 
Although there is a consensus among academia that fasting is more beneficial for health than negative, the results of this research remain controversial and require further research [22,23].
The two most popular forms of fasting in the West appeared in the first half of the last century.
1. Water fasting according to Shelton , practiced in the United States, which involves the exclusive consumption of water during the fasting period.
2. Buchinger’s method , practiced in Europe, which provides for the exclusive consumption of liquids, fruit juices, vegetable broths and honey up to 200-500 kcal per day.
In both cases, fasting is generally practiced in specialized clinics or naturopathic centers and under medical supervision (for example, in France, in fasting and hiking centers). You can choose to practice this type of fast independently at home, but it is recommended that you do so.
regularly monitored by a health professional. .
• Transition to ketosis (detectable by an increase in the number of ketones in the blood): after at least 4 to 5 days of MMD, lipid metabolism is triggered. This energy gets its energy mainly from body fat (instead of glucose, the storage of which is usually depleted after a few days). This results in a strong weight loss.
• Activation of autophagy: this is a process that helps maintain healthy cell function and encourages cells to repair, renew or regenerate .
• In intermittent fasting and interval fasting, there is no clear indication that MMJ triggers these mechanisms at the cell level.
• Any contraindications must be ruled out beforehand by experts.
• Exiting the fast should be watched and carried out with care. In other words, the resumption of eating should be done gradually over several days.
• It is strongly advised not to lead this type of fast, only under the supervision of experts, because it is not suitable for people suffering from certain diseases, and there are risks of side effects such as headaches, hypoglycemia and fainting.
• Not very practical for those who do not have the time and money to invest in a therapeutic stay.
PUT INTO PRACTICE
It is recommended to apply to institutes that deal with this type of fasting.
The following addresses may be useful for research:
- www.inserm.fr/sites/default/files/2017-11/Inserm_ RapportThematique_EvaluationEfficaciteJeu- ne_2014.pdf
In all cases, the fasting program should be set up with a qualified healthcare professional. Typically, clinical and blood tests are done before, during, and after fasting to rule out any health problems or nutritional deficiencies.
Fast Mimicking Diet (FMD)
Fast Mimicking Diet (FMD) is a scientifically advanced form of fasting, implemented by Professor Valter Longo and his research team at the University of Southern California. The products to be taken during this assisted fast are specially designed to allow MMJ. It is marketed as ProLon®, a kit containing granola bars, freeze-dried soups, crackers, olives, beverages and dietary supplements. It is a low-calorie diet that lasts 5 days and whose nutritional contribution is adapted to the person’s weight.
It provides about 1100 kcal the first day and 800 kcal the other 4. Calories are divided by 50% into predominantly unsaturated fatty acids and 50% into complex carbohydrates with a low glycemic load. The percentage of protein is minimal. Supplements of vitamins, minerals and omega-3 fatty acids are also present.
This approach to periodic fasting has led to a fundamental change: it can be performed without special precautions by a healthy adult (20-70 years). In France, the program is sold on prolon-france.fr
Worldwide, more than 100,000 people (as of 2019) have already applied the ProLon® assisted fasting program without major complications. The contraindications are as follows:
• Pregnancy or breast-feeding
• Eating disorders
• Symptoms of infection
• Malnutrition or BMI ≤ 19
In addition, other aspects to be aware of before taking the program are described on the website at the time of sale (such as not doing strenuous sporting activity while taking the assisted fast). The resumption of food after the 5 days of assisted fasting is done independently by following the recommendations provided in the kit.
Clinical studies have shown that this form of 5-day assisted fasting (repeated every three weeks over a period of three months) reduces risk factors for type 2 diabetes, cancer and cardiovascular disease  and promotes thus longevity and cell renewal for good overall health. Preclinical studies in animals and cells also show beneficial results in the following areas:
• Type 1 diabetes 
• Multiple sclerosis 
• Irritable bowel syndrome 
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• The advantages are the same as for water fasting (autophagy, cell renewal). However, they are achieved within 5 days and with three meals a day.
• Daily activities can be continued, provided that there is no work involving exhausting labor (eg construction workers).
• ProLon® can be done directly at home, so it is less expensive than water fasting which is done in the clinic.
• ProLon® is more easily tolerated since it preserves meals. It is also more suitable for everyday use than water fasting and is therefore an excellent introduction to the practice of fasting.
• The kit is well structured and easy to use: the foods for the 5 days are divided into 5 numbered boxes for each day of the program.
• It is not suitable for people who are allergic to the ingredients in the kit, including tree nuts, soybeans, oats, sesame, celery and celeriac.
• Certain ecological and sustainable aspects are not taken into account: the packaging generates a lot of waste *. In addition, some foodstuffs are imported from distant countries (United States, North Africa).
• * A green implementation of ProLon® is already underway.
PUT INTO PRACTICE
One possibility is to follow the study protocol described below: one cycle per month for three months (with a 25 day break between each cycle). It is recommended to do this 1 to 4 times a year. In the book The Longevity Diet, which we advise you to read , Professor Longo, author of the study, suggests practicing FMD at a frequency proportional to your health (obesity, a risk factor for diabetes , cancer, cardiovascular and neurodegenerative diseases) and the advice of your general practitioner.
Fasting has many positive effects on health, which goes far beyond simple weight loss. We recommend considering it as a way to stay healthy and manage stress better – just as physical activity allows – but also as a new start towards a healthier diet and lifestyle. Fasting has always been available to everyone. But perhaps it is time, in light of these latest findings, for the general public to embrace what science has to offer.
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