Periodic Food Intake Restriction - Learn About Its Principles!

Intermittent fasting, commonly termed as IF, is a nutritional approach that revolves around consuming food only for a specific duration within a day or week, while consciously refraining from eating during the remaining time. There are numerous variants of this fasting approach. The most favored one is 16/8, in which we fast for 16 hours and ingest meals within an 8-hour feeding window. In practical terms, this means forgoing breakfast in the morning, partaking in the first meal at midday, and the last one no later than 8:00 PM. The length of the feeding window should be tailored individually to ensure adequate food intake for meeting energy and nutrient requirements. Individuals adhering to stringent norms might opt to shorten the feeding period, for instance, to 4 hours. Another method, known as 5/2, entails implementing a substantial caloric restriction for two successive days per week, whereas we adhere to our normal diet for the remaining five days. It is crucial to underscore that irrespective of the chosen fasting method, the quality of consumed products holds significance. They should be minimally processed and abundant in vitamins and minerals. Fast food, sugar, pre-packaged snacks, alcohol, and others should be eschewed. Adequate hydration is equally vital. Apart from mineral water, unsweetened black coffee or tea can be consumed in smaller quantities.

Fasting is a natural process for mammals. The human body is remarkably well-adapted to the challenge of limited food availability. During periods of fasting, when the body's glucose supplies are depleted, alternative energy pathways are activated. The liver then produces so-called ketone bodies, which serve as fuel for the body's cells. This occurs due to the activation of glucagon, the hormone antagonistic to insulin. Insulin, on the other hand, is primarily responsible for increasing body mass, including both muscle and fat tissue. In individuals with low physical activity, excess insulin results in the accumulation of unnecessary weight in fat tissue. Limiting the amount of secreted insulin enhances cell sensitivity to this hormone, improves fasting blood glucose levels, and allows for the release of stored fat reserves. Intermittent fasting is, therefore, a highly beneficial tool in preventing diabetes and combating insulin resistance. Many people fear that reducing the number of meals will have the opposite effect, leading to weight gain. However, research has shown that the rate of metabolism remains the same, regardless of how we distribute the number of kilocalories consumed throughout the day. Short-term fasting (lasting up to 48 hours) can even increase resting metabolic rate by 3.6-14% due to higher levels of noradrenaline in the blood. However, for longer periods, the opposite effect occurs, making periodic fasting a better solution. Apart from energy balance, other aspects are also important, primarily the degree to which food components are absorbed in our intestines. This is related to, among other things, the state of the gut microflora. IF aids in weight reduction by regulating hormones responsible for hunger and satiety - ghrelin and leptin. As research shows, periodic fasting has a cardioprotective effect. Firstly, it lowers blood levels of homocysteine, triglycerides, and LDL cholesterol fractions, which contribute to the development of atherosclerosis. Secondly, cyclic fasts help reduce blood pressure, decrease oxidative stress in cells, and reduce inflammatory markers - interleukin 6 (IL-6), CRP, and TNF-alpha. Another advantage of intermittent fasting is improved body regeneration. The process of autophagy, the destruction of old, worn-out cells, is intensified. In many individuals following this system, brain function, sleep quality, memory, concentration, and overall energy levels improve. Studies on both animals and humans indicate that periodic fasting may have anti-cancer effects and extend lifespan by activating sirtuins, the longevity genes.

Periodic fasting can be an effective solution for individuals with glucose-insulin disorders and obesity along with its accompanying leptin resistance. The reduction of insulin secretion and the suppression of appetite significantly facilitate the weight loss process. Additionally, it can improve the health of individuals with high risks of atherosclerosis, diabetes, and heart diseases. Among those who derive the greatest benefits from periodic fasting are shift workers, as IF helps regulate the daily rhythm. An additional advantage of limiting food intake is the time savings, as it is not necessary to prepare multiple meals per day, which is particularly relevant for those who travel frequently.

Periodic fasting is not the ideal way to eat for everyone. Some people may find it very difficult to go without food for many hours, especially at the beginning. During the adaptation period, dizziness and fatigue may occur. Before the body can effectively use ketone bodies, it will require fuel in the form of glucose, which will make it easier for the body to eat and eat sweets and other snacks. There is also a greater risk that the desire to eat more food will occur, especially in the beginning of the diet. This can also lead to excessive fasting and fat loss. This is also not recommended for people with reactive hypoglycemia. Such people should eat more often during the day to prevent a drastic drop in blood sugar levels. Skipping meals can disrupt the production of digestive enzymes. If the digestive system is in a sleep state for most of the day and then forced to process a large amount of food, digestive problems may occur. However, this is not a rule, as in some people (e.g. those suffering from gastroesophageal reflux) there is often a noticeable improvement. If our health condition raises doubts, we should consult a doctor before starting the diet. Every body is different, so it is difficult to predict all reactions to a change in diet. One of the negative effects may be an increase in stress, as the body is first exposed to prolonged hunger and then to overeating. Excessive calorie restrictions, which often accompany periodic fasting, contribute to hormonal imbalance in women, leading to the cessation of ovulation. For this reason, IF may be inappropriate especially for women with low body fat. Women who use this system should be careful not to shorten the eating window too much. Ideally, it should last 8, if not 10 hours. Another problem is the difficulty in meeting daily energy needs and all nutrients in just 1-2 meals a day. An overweight patient on a reducing diet should be in a calorie deficit. However, if we are dealing with someone who performs heavy physical work or trains intensively in the gym, the matter looks completely different. Although of course this is not a rule either. Many athletes praise IF, as it helps them gain pure muscle mass while maintaining a low body fat percentage. Studies have shown that during fasting, the level of growth hormone (somatotropin) in the blood increases. Periodic fasting can be problematic if we have previously eaten meals with family or friends and if our work requires frequent participation in business meetings during lunch. We should then consider whether we have enough willpower to refuse a common meal. In addition, intermittent fasting should not be used by children, pregnant women, or people who do heavy physical work.

Periodic abstinence from ingesting food can constitute an effective method for weight loss, however scientific investigations have not confirmed the superiority of this nutritional model over the traditional diet in the context of weight reduction. The IF diet can also contribute to improving mental health and preventing or treating certain ailments. It is particularly effective in individuals afflicted with metabolic syndrome. However, similar to other nutritional models, it also has its disadvantages. Prior to deciding to commence intermittent fasting, one should consider their lifestyle, degree of physical activity, and goals to be achieved. The diet should be tailored to one's needs and health status in order to achieve maximum benefit.