An intro guide to the different methods of fasting
Intermittent fasting, 5:2 method, time restricted eating....there are so many different methods of fasting that it can get a bit confusing on the differences and outcomes of each. However, fasting is not new. Humans have done a form of fasting, either purposefully or due to food shortages, for most of our existence. Over the past few years Intermittent Fasting (IF) has been getting a lot of buzz, and not without reason. Let's do some digging to see if fasting is for you. Please note, I am not advocating for fasting. This is for educational purposes only.
Types of fasting-
Intermittent fasting: an umbrella term for periods of eating and then fasting. Includes time restricted eating, fasting mimicking diet, 5:2 method. This is just about times of eating, so no guidelines on what to eat. Unfortunately, people may think they can eat whatever they want, as long as its within the time frame of eating. This is false- what and how much you eat still matters. IF is a lifestyle change!
Time Restricted Eating: Eating within a window of time, every day. Common windows are- 16:8 (fasting for 16 hours, eating in an 8 hour window), 18:6, 20:4, 22:2 (OMAD- one meal a day). Again, there are no rules on what to eat, so there is a risk of making poor food choices. As we go longer without food, hunger and appetite are more difficult to control. This may not be for you if fasting every day seems like a challenge. Many people tend to skip breakfast, as it is easier than skipping dinner. However, studies have linked skipping breakfast to higher risk of cardiovascular disease. Furthermore, we need energy more during the day than night, and excess calories are more likely to be stored rather than burned when eating at night.
5:2 Method: This method uses two days of the week to significantly decrease caloric intake (about 500 calories a day). For the rest of the five days, you should eat normally. Like time restricted eating, this is a lifestyle change.
Eat-Stop-Eat: Similar to the 5:2 method, people will completely fast 1-2 days a week and eat normally on other days.
Fasting Mimicking Diet: 5 day-long periods of low calorie, high fat intake. ProLON is the most well known FMD protocol. Calories are about 35-40% of normal intake. Should be repeated every few months for optimal results. Unlike the above methods, FMD isn't happening on a regular daily or weekly basis for the most part so it can be easier in a way to incorporate.
Benefits of fasting:
Extensive research has be done around IF, and for the most part each method does this same thing and include
Reduces blood pressure
When we fast, our body's preferred storage form of energy- glycogen- begins to deplete. In order to maintain normal function, our body will use a different form of energy storage- our fat. Fat will be broken down and used as fuel, leading to the formation of ketone bodies. This is where ketosis comes from. Furthermore, cell turnover increases during this time. Since our body is in an energy deficit, it will keep replacing parts of our body in order to maintain itself leading to "newer" cells. Its important to note though, that these new parts are coming from our muscles. which is why long fasts can lead to muscle degradation.
The benefits of fasting increase with the duration of the fast, and we see the main benefits appear at the 24 hour mark. It is inadvisable to start IF with a long fast. Work your way up, starting with a 12 hour fast and adding in an hour each time. The long fasts (+24 hours) are not meant to be done very often, 1 or 2 times a week maximum. Personally, I would not recommend fasts longer than 16 hours to do on a daily basis. It can lead to overindulgence and is difficult to get your caloric needs in small windows of time.
When fasting may not be appropriate:
Some doctors say that women should not fast for more than 14-15 hours as it can disrupt hormone function and menstruation
Women who are pregnant/breastfeeding
People with hormone issues (ex- diabetes)
Individuals with a history of an eating disorder
Low blood pressure
Fasting can be an incredible health tool, when used properly. It is always important to talk to your doctor about whether fasting is right for you.