IF diet is becoming more and more popular. It raises many controversies among dietetic experts. Its supporters highly praise it, opponents find hundreds of arguments against its use. I will try to explain what it is and by whom it can be used.
the IF diet - what is it?
Intermittent fasting (IF for short) is a way of eating that involves taking in food only for a certain amount of time during the day or week, the rest of the time you intentionally abstain from food. There are different versions of intermittent fasting. The most popular is 16/8, in which we fast for 16 hours and eat meals in an 8-hour eating window. In practice this means that you skip breakfast in the morning, eat your first meal at noon, and your last meal at 8 p.m. at the latest. People who are strict about it, shorten the time of the window, for example to 4 hours.
Another method called 5/2 involves a lot of calorie restriction for 2 consecutive days a week, and for the remaining 5 days - we follow our usual diet. It should be noted that whatever type of fasting you choose, the quality of the foods you eat is important. They should be low-processed, full of vitamins and minerals. You should avoid fast food, sugar, ready-made snacks, alcohol, etc. Do not forget about proper hydration. In addition to mineral water, you can drink unsweetened black coffee or tea in smaller amounts. Chewing sugar-free chewing gum is also acceptable.
Why eat this way?
Fasting is natural for mammals. The human body is perfectly adapted to a limited access to food. During a fast, when glucose reserves in the body are depleted, alternative energy pathways are activated. The liver produces so-called ketone bodies, which provide fuel for the body's cells. This is due to the activation of glucagon, a hormone antagonistic to insulin. Insulin, in turn, is mainly responsible for increasing body weight, both muscle mass and body fat.
In people with low physical activity, excess insulin results in the accumulation of excess weight in adipose tissue. By reducing resting insulin secretion, the sensitivity of cells to this hormone increases, fasting glycemia improves, and stored fat stores can be released. Intermittent fasting is therefore a very helpful tool in the prevention of diabetes and in the fight against insulin resistance.
Many people fear that reducing the number of meals will result in the opposite effect, i.e. weight gain. However, studies have shown that the metabolic rate is the same no matter how you divide the number of kilocalories consumed during the day. Short-term fasting (up to 48 hours) may even increase resting metabolism by 3.6-14% due to higher levels of norepinephrine in the blood. However, for longer periods of time the effect will be the opposite, so intermittent fasting is a better option. Apart from energy balance other aspects are also important, first of all the extent to which nutrients are absorbed in our intestines. This is related, among other things, to the state of the intestinal microflora. IF helps in weight reduction also due to regulation of hormones responsible for the feeling of hunger and satiety - ghrelin and leptin.
Research shows that periodic fasting has a cardioprotective effect. Firstly, it lowers blood levels of homocysteine, triglycerides and LDL cholesterol fractions, which contribute to atherosclerosis. Second, cyclical starvation helps lower blood pressure, reduces oxidative stress in cells and inflammatory markers - interleukin 6 (IL-6), CRP and TNF-alpha.
Another advantage of intermittent fasting is better regeneration of the body. The processes of autophagy, i.e. destruction of old, worn out cells, are intensified. Many people who use this system improve brain function, sleep quality, memory, concentration and overall energy levels. What's more, studies on both animals and humans show that intermittent fasting can have an anti-cancer effect and extend life by activating sirtuins, or longevity genes.
Who will the IF diet be suitable for?
Intermittent fasting may be a good option for people with glucose-insulin disorders and obesity and associated leptin resistance. By reducing insulin secretion and suppressing appetite, it significantly facilitates weight loss. In addition, it can contribute to better health in people with a high risk of atherosclerosis, diabetes, heart disease and inflammation.
Shift workers will benefit, as IF helps regulate the daily rhythm. An additional advantage of reducing the amount of food is saving time. It is not necessary to prepare several meals a day, which is important especially for those who travel frequently.
Disadvantages of IF
Intermittent fasting is not an ideal diet for everyone. Some people find it very difficult to go many hours without eating, especially in the beginning. You may experience dizziness and fatigue during the adaptation period. Before the brain can use ketone bodies effectively, it will demand glucose fuel, making it easier to give in to cravings and reach for sweets and other snacks. There is also a greater risk that cravings will arise to compensate for hunger. This puts you at risk of consuming excess calories and foods that are not very healthy. IF is also not recommended for patients with reactive hypoglycemia. Such individuals should increase the frequency of food intake throughout the day to prevent blood sugar levels from dropping too drastically.
Skipping meals can interfere with the production of digestive enzymes. If the digestive system is dormant for most of the day and then is forced to process a large portion of food, digestive problems can occur. This is not the rule, as some people (such as those suffering from gastroesophageal reflux) often have noticeable improvement. If our health is in doubt, consult a doctor before starting a 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 the feeling of stress, because the body is first exposed to many hours of hunger, and at other times to overeating.