Intermittent fasting (interval fasting), also called short-term fasting, is a dietary method which has gained more and more popularity in recent years.
There are several variants of this diet. However, as the name suggests, all variants aim at fasting within a certain period of time (interval). So, in essence, you do not eat any food within a particular period of time.
However, fasting is exclusively about food. Liquids are allowed. So water, tea, and coffee are allowed. However, it is important when fasting that you avoid caloric drinks such as juices or sodas.
During the period you set for yourself to eat, you can eat and drink normally, so any restrictions only apply during the fasting period.
The most popular methods of interval fasting are the 5:2 method, alternate fasting (Eat Stop Eat), OMAD (One Meal A Day), interval fasting 20:4 (Warrior Diet), and interval fasting 16:8 (Leangains Method).
With the 5:2 method, you eat normally five days a week. The remaining two days you drastically reduce your calorie intake and consume only 500-600 cal. Alternate fasting works in a similar way, but with A and B days. On the A days you eat normally and on the B days you eat nothing or consume very few calories. An A day is always followed by a B day.
So, both methods aim to consume no calories or very few calories for the period of one day.
The One Meal A Day method means that you eat only one meal a day. This meal is relatively large, since you are combining all the meals you would normally eat in a day into one meal.
The Warrior Diet (20:4 interval fasting) is similar. Here you fast for 20 hours and eat your calories in a 4-hour window. The name of this method comes from the prehistoric people who allegedly had a similar eating schedule. They hunted during the day and ate in the evening.
The most common and widespread method of interval fasting is the Leangains method (16:8). In this method, you fast for 16 hours and have the remaining 8 hours to provide your body with nutrients. Often the last meal is eaten at 8pm and you fast until 12 noon. However, if another window would suit you better, you can customize based on your individual needs.
Fasting can increase your cell production and cell regeneration. Furthermore, your insulin level is lowered, which can prevent diseases such as type 2 diabetes. In addition, the hormone leptin is regulated, which is responsible for your feeling of hunger. Thus, you have a much better feeling of satiety.
So in terms of fat loss, intermittent fasting can offer significant benefits. However, any calorie-reduced diet offers such benefits, so this type of fasting is not mandatory. Choose a diet that will give you long-term success.
Fasting tends to have a negative effect on muscle building. You certainly can fast and build muscle, but protein biosynthesis is probably not triggered optimally. So, if you want to build muscle, you should eat protein-rich foods regularly.