Intermittent fasting may have several health benefits, including lowering blood pressure, delaying aging, and even being beneficial in cancer treatment. Fasting has also been shown to increase mental focus and improve sleep.
There are several different forms of intermittent fasting, including the 5:2 method and the 16:8 method.
Intermittent fasting is a dietary practice that alternates between periods of fasting and eating. The health purpose of fasting is to allow the body to rest and recover. The body, which uses the salivary glands, liver, gallbladder, and pancreas during digestion, gets the necessary rest and time to repair cell damage during a period of fasting. Like other systems in the body, the digestive system needs rest to function optimally.
One way to do intermittent fasting is called the 16:8 method, which involves eating as usual for 8 hours and fasting for the remaining 16 hours of the day. It is common to eat dinner around 6 or 7 pm and eat again at 10 or 11 am the next day. It is said that you should be able to spend these hours as you wish, but some say that you should not eat after 6 pm for the best effect. A similar but "kinder" approach is to use an equivalent 14:10 method instead. There are also "upgrades" to 18:6 for those who want to fast longer.
Another common method is 5:2, where you eat as usual for five days and "half fast" for two days. On the half-fast days, you eat about 500-600 calories of nutritious food. It is also possible to do a more gentle 6:1.
Health benefits
According to Kerstin Brismar, Professor of Diabetes Research at Karolinska Institutet, regular intermittent fasting can have a number of positive health effects, including on blood pressure, blood lipids and gut flora.
– People who fast often find that they are more alert, happier and sleep better, she told the magazine Må Bra.
A 2015 animal study showed that intermittent fasting changed the gut flora, to the great benefit of good bacteria. Another study published in 2019 showed that intermittent fasting can lead to significant improvements in liver steatosis, especially in people with type 2 diabetes. The results suggest that both people with and without diabetes experience a reduction in liver fat and body weight with this type of fasting.
Intermittent fasting is often promoted as a good way to lose weight, but a 2021 study suggests that this may not be true. The study tested three groups, one using intermittent fasting, one using a traditional diet, and one using only partial fasting. The intermittent fasting group lost almost no weight over three weeks, while those on a traditional diet lost 1.9 kilograms
However, you can still lose weight with intermittent fasting, for the simple reason that you often don't eat as much as when you're not fasting. Fasting can also reduce appetite, which in itself can also lead to weight loss.
– Counterintuitively, fasting has been shown to decrease the hunger hormone ghrelin, nutritionist Whitney English told Livestrong.
The reason why fasting can make you feel more alert and energetic may be because the body enters a metabolic state called ketosis, which means it switches from using glucose to using ketones instead.
– Researchers call this 'intermittent metabolic switching' and believe that it adapted to help humans remain in a state of optimal functioning in order to hunt and gather food during periods of hunger, Whitney English explains.
Fasting is also thought to improve insulin sensitivity, which may protect against diabetes. It may also help lower blood sugar, improve blood lipids, and lower blood pressure, according to Livestrong.
Slowing the aging process
Professor Valter Longo of the University of Southern California has spent more than 15 years researching fasting and its health effects, and has concluded that restricting calories through fasting can prolong life. In one of his studies, participants completed three rounds of five-day fasts, interspersed with a low-sugar, low-protein diet. The results showed that the biological age of the participants decreased by an average of 2.5 years.
– We clearly see in our laboratory studies that organs and cells shrink and then rebuild. The body turns on the stem cells and starts to rebuild, said Valter Longo in the SVT program Vetenskapens värld in 2022.
Longo has also done some research on cancer and believes that fasting can help in cancer treatment. Back in 2012, he showed that fasting together with chemotherapy can shrink tumors more than chemotherapy alone, because fasting prevents cancer cells from getting the nutrients they need to grow. However, fasting can also cause nutritional deficiencies in patients, so a fasting-like diet has been developed that deprives cancer cells of the nutrients they need while still providing important immune system cells with what they need. In later trials, in 2016, this fasting-like diet was tested together with chemotherapy in cancer patients and found to work, according to an article from forskning.se. On his website, Lango describes the diet and other research he has done.
How to start intermittent fasting
If you want to start some form of intermittent fasting, it can be good to start slowly and gradually, for example, fast for twelve hours and see how it feels, then gradually increase to longer periods. Then you can test the waters and see what type of intermittent fasting works best for you. Some may want to alternate between 5:2 and 16:8, while others may only want to use the 14:10 method.
It is also important to eat good, nutritious food during the eating periods. Make sure you get enough protein, fiber, fats, vitamins, and minerals. Remember to drink plenty of water, especially during fasting periods..
During these fasting periods, it is okay to drink coffee and tea as well as water.
Be sure to listen to your body. If you feel nauseous or dizzy, you may want to break your fast.
Fasting should always be avoided if you are pregnant, underweight, under the age of 18, or have an eating disorder. If you are taking any medications, you should also ask your doctor if intermittent fasting is okay for you.
