Intermittent Fasting

Intermittent fasting has been gaining more and more popularity, especially amongst the low-carb and ketogenic community.  I’ve been getting many questions from patients regarding its benefits and the different styles of implementing various types of fasts.  I will outline some of the techniques and benefits here. 

The most popular intermittent fast (IF) is 16:8.  This advocates a fasting period of 16 hours with an 8-hour eating window.  For example, someone on this fast would stop eating by 7pm and have their first meal the following day at 11am.  So from 7pm-11am, there is a 16-hour period of no calorie intake.  Note: water, unsweetened tea, and black coffee are fine during the fasting period.  This could be adapted to whatever 8-hour window is most preferable; i.e. 10am-6pm; 8am-4pm, etc.  Other styles of fasting are 5:2 (5 days of eating normally with 2-consecutive days of fasting), spontaneous meal skipping (i.e. skipping lunch), the Warrior Diet (a 4-hour eating window with an emphasis on the Paleo or Ketogenic diet), and the Eat-Stop-Eat fast (24-hours of fasting; i.e. 6pm-6pm).  All of these fasting techniques have various benefits, but the most convenient and consistent to employ is IF with 16:8. 

Fasting has been shown to drastically benefit longevity.  It does this through a number of different mechanisms. Autophagy is process that every single one of our cells goes through.  When we exercise, think, breathe, and go about our day-to-day activities, our cells burn energy and build up metabolic waste.  Just like the garbage we accumulate in our houses that eventually need to be disposed of, our cells accumulate wastes that need to be taken out.  Autophagy acts as a way to cleanup, recycle, and renew this buildup.  If this doesn’t happen, we get bogged down and experience a slew of symptoms like fatigue, headaches, memory issues, and depressed moods. Fasting has been shown to increase this process of autophagy, which liberates energy, improves our metabolism, and preserves lean muscle mass.  Side note: guess what else drastically improves autophagy…sleep!

Fasting has also been shown to increase two brain chemicals: brain-derived neurotrophic factor (BDNF) and fibroblast growth factor (FGF).  These both act to enhance our ability to make memories and learn new skills, a process known as synaptic plasticity. This plasticity is what allows kids to be able to learn new languages more quickly than adults.  Also, fasting helps preserve the neurons that produce serotonin and dopamine.  Serotonin is the feel-good neurotransmitter that’s often blamed for being low in depression and dopamine is the get-up-and-go neurotransmitter that causes feelings of excitement and elation.  Consequently, depression has been shown to improve through therapeutic fasting (serotonin) and dopamine-deficient disorders, like Parkinson’s disease, have been shown to also benefit from fasting.  

Lastly, insulin sensitivity has been shown to improve through intermittent fasting.  Insulin is a hormone that helps use gain access to energy in our body.  It acts like a key that opens the doors in our cells to let energy in.  If this key doesn’t work well, then our body can’t gain access to the energy and we’re left feeling tired and hungry.  Fasting increases our body’s ability to respond to insulin, allowing it to work even better at opening these doors.  This has profound benefits of improving metabolism, decreasing body fat, and decreasing the hunger signals that cause us to overeat. 

There are so many more benefits to intermittent fasting that will have to be saved for another post, but hopefully these will provide some bite-sized benefits and strategies to start playing around with.