Intermittent fasting (IF) is not a diet as much as it is an eating style. Intermittent fasters wait anywhere from 12-48 hours in between meals with the idea of getting the body into a fasting state. In our current 3-square-meals-a-day food culture our bodies never get a chance to “rest and reset”. In human history we have always had periods of feast and periods of famine. Our bodies are set up to do specific jobs in each state. Now with 24-hour grocery stores and food delivery services we spend all of our time in a state of nutritional cellular abundance.
Cellularly speaking there are two roads a cell can be on. A fed road or a fasted road. On the fed road the cells are in a period of acquisition and accumulation. They are taking in glucose and nutrients, using what they need, and storing the rest. In this state insulin is high and glucose is high. This is a state of bounty. Like a harvest, this is when nutrients are plentiful. Also, like a harvest, it is a time when the excess is stored for later. The body stores all of the extra glucose in the form of glycogen. Glycogen, a stored form of carbohydrates, is tucked away in the tissues and in the liver for use for creating energy when we are in a fasted state.
The fasted road is the state where the body is using up the stored fats and carbohydrates for energy. In the first stage of the fasted state the body uses up the stored glycogen in a process called glycolysis. In the second stage it starts using up stored fat in a process called ketosis. Though glucose is the body’s preferred fuel source, it adapts pretty quickly to the transition between using stored glucose to using ketone bodies (or fats) for energy.
In ketosis the body is able to go into an essential cellular recycling process called autophagy. This process is unique to a fasted state. Autophagy, a Greek term for “self-eating,” is a way for the body to clean up and eliminate damaged cells. This can initiate molecular changes in the body that can improve cellular repair and gene expression. According to Registered Dietician Felicia Stoler, autophagy is a critical cellular process for proper immune system function and possibly, longevity. In 2016 the Nobel Prize in Physiology and Medicine was awarded to Cellular Biologist Yoshinori Ohsumi for his work in identifying and observing this extraordinary cellular phenomenon.
It should be noted here that IF, though very good for your body, should not be taken to extremes. Although ketosis can trigger cellular clean-up, it can also cause cellular death when incurred over long periods of time. The key with proper IF is to have designated periods of fasting followed by periods of consuming nutrient-rich whole foods.
4 main styles of IF:
- 16-8– The baseline for fasting is 12 hours of fasting (including sleep) followed by an eating window 12 hours. This does not mean eating for 12 hours straight! It means eating a normal diet in the 12 hours where eating is permitted. Working up to a 16-hour fasting period with an 8-hour eating window is recommended as it allows for a longer amount of time in ketosis. Typically, people choose the 12 noon to 8pm eating window as it is the most sustainable. It’s basically skipping breakfast and eliminating late night snacking.
- 5 and 2– This type of intermittent fasting is eating a normal diet with no designated fasting periods for five days, and then spending two days a week eating only 500 calories per day.
- The Warrior– This style of IF is fasting with nothing but water for 24 hours 1 day per week.
- 5 Day Fasting Mimicking– This diet limits carbohydrates and proteins, both of which can be turned into glucose, and focuses on a low level of fat-based foods for a period of 5 days. This tricks your body into thinking it’s fasting while you are eating. Having your body in ketosis for a 5-day period allows your body to do the maximum amount of cellular repair and encourages the body to produce new intestinal stem cells, giving you, essentially, a “reset” button. It is recommended by Dr Victor Longo, creator of the ProLon system, that this style of diet be done once per month for 3 months every year.
The Intermittent fasting schedule you choose is up to you. The one that fits best into your lifestyle is the one that you will be able to maintain. As always, I recommend consulting with a nutritionist before initiating any dietary changes to ensure that it is safe for you.
By Tapp Francke Ingolia
as seen in The Purist Magazine