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I respect the ketogenic diet, intermittent fasting is a food program that involves regular and specific programming of the times when you can eat. Several studies show that it is a way to keep body weight under control and prevent diseases related to being overweight. But how does it work? And is it safe?

What is Intermittent Fasting

Many diets focus on what types of foods to eat. Intermittent fasting, on the other hand, focuses on when to eat. With intermittent fasting, in fact, you can only eat during specific time windows, while for the rest of the day you will be fasting or have meals but only on certain days of the week. It is a method that has been shown to be useful not only for losing weight, but also for improving one's health.

In particular, intermittent fasting was the subject of a 25-year study by a neuroscientist at Johns Hopkins University. The results that emerged show that our body has the ability to go for certain periods without eating. Several hours, but in some cases even days. In the prehistoric era, before humans learned farming and herding, hunters and gatherers evolved to survive without eating even for long periods, all while also using a lot of energy to hunt and gather berries and nuts.

Even 50 years ago this regimen was more popular, and it was easier to maintain a healthy weight. Nutritionists point out that without computers and television – at least not until late – people tended to stop eating and go to bed earlier, portions were smaller, and more people worked or spent their free time outdoors exercising, in general line, more physical activity.

Nowadays, however, between television and the internet we tend to stay awake for more hours and eat more often and in a less healthy way. But this also means a greater risk of developing obesity, type 2 diabetes and other disorders on which intermittent fasting could have a positive effect.

intermittent fasting

How does intermittent fasting work?

Intermittent fasting can be done in several ways. The essential thing is that they are all based on a rigid determination of the time windows in which one can eat and those in which one is fasting. For example, you may choose to cram all of your meals into an eight-hour window, and fast for the rest of the day. Or you no longer choose to eat dinner only two days a week. The programs are very different from each other and suitable for all needs.

After hours without eating, the body runs out of sugar and begins to burn fat. That's why there is a metabolic switch, as well as a change in habits, prolonging the period of time in which the body burns fat rather than calories just ingested with meals.

The different intermittent fasting plans

Important, when you decide to start intermittent fasting, is to talk to your doctor to get the green light. Once this is done, practicing fasting is really simple. You can also try a daily approach by changing day to day to see what works for you. For example, open a six- or eight-hour window during the day and concentrate all your meals in that window, but vary the time from day to day: this is the 16/8 fast, where you eat for eight hours and fast for sixteen, and is considered the easiest to follow in the long run.

Another very popular variation is the 5/2 approach: it means eating regularly five days a week, and limiting yourself to 500 calories per meal for the remaining two days. For example, eat normally from Monday to Friday, and then at the weekend do not go over the recommended calories.

Long periods without food, for example from 24 to 72 hours, are not necessarily the best choice for everyone and can even be dangerous in some cases. Going too long without eating can also push the body into famine mode and stop burning calories to conserve itself.

According to research, it can take two to four weeks for your body to get used to intermittent fasting. During this period, it is possible to feel hungry or tired. However, usually those who start the fast do not break it, because they also begin to feel better, actively feeling the health benefits.

intermittent fasting

What can you eat during intermittent fasting?

During the fasting time, i.e. the hours when you don't eat, only water and calorie-free drinks such as tea and coffee are allowed. While during the window of time in which you can eat, you can do it "normally". This doesn't mean giving in to everything. If the goal is to lose weight or take care of one's health, foods should be healthy and low in calories. Not junk food and not giant portions, in short. 

The positive note of intermittent fasting, however, is that you do not have to select the permitted foods. You can eat anything, including carbohydrates and fats. And there are therefore no restrictions that lead, for example, to avoid eating in company. A good example? Follow the recipes of the Mediterranean diet, alternating fasting with the consumption of healthy and varied food that gives the right amount of carbohydrates, proteins and vegetable fats.

The benefits of intermittent fasting

Studies show that intermittent fasting isn't just about losing weight. The metabolic change it causes, in fact, also affects the body and the brain. The benefits associated with the practice of intermittent fasting also include an extension of life. This is because what happens during the fast protects the internal organs from the risk of chronic conditions such as type two diabetes, heart attack, and age-related neurodegenerative disorders, as well as the internal inflammatory events that underlie many cancers.

But not only that, because studies have also shown improvements in concentration and memory. As far as the cardiovascular system is concerned, there have been improvements in blood pressure and blood sugar levels. Improvements also in athletic performance, also linked to weight loss. And a sensitive contrast to diabetes and obesity. And finally, benefits for the skin.

Is intermittent fasting a healthy choice? 

Decidedly. Intermittent fasting helps not only with weight loss but, as we have seen, with numerous other conditions. However, it's not for everyone. Children under 18, pregnant or nursing women, and people with a history of eating disorders should avoid fasting.

More generally, it is always advisable to follow the fast after consulting with your doctor, even with check-ups if anxiety levels increase, or if you have headaches and nausea.