5-min Reads - Intermittent Fasting

Health and Fitness Topics Explored with Kyle in 1,500 Words or Less

From the community: What are your thoughts on intermittent fasting?

Intermittent fasting has grown in popularity over the last few years and is becoming more and more popular as more people try it out.  I don’t like to give too much advice about things that I have not fully tested myself or have not actually been able to see any benefits from. Since this topic falls into that category, I’ll talk more about what I’ve heard and what sounds like good solid science to me, but this is more of a regurgitation piece than a research article.

First of all, terminology on intermittent fasting gets thrown around, so let’s clear up some definitions quickly.  Intermittent fasting refers to normal periods of food intake with extended periods of low-to-no food intake.  This can be accomplished in many different ways and I have yet to hear definitively which ways are best, if any. 

All of these would fall in the category of Intermittent Fasting techniques:

Periodic Fasting – Every so often, maybe a few times a year, people fast 3 days upwards of months or even as long as a year…yes there have been stories of extremely overweight people not eating for a full year!  Research shows that eating small amounts may be more difficult than not eating at all.  Your hunger hormones actually lower when you eat no food, but they stay at relatively the same levels when you are eating small amounts of food.  Some anecdotes I’ve heard from these periodic fasters is that the first couple of days are the hardest as you fight the hunger sensations.  After that, they just don’t feel hungry.  Some say, they don’t plan the length of their fast.  It may be 7 days or 30 days, but they simply just eat again when they get hungry again. After the first couple of days their bodies start using their fat reserves for energy.  It also appears that there may be little to no muscle mass loss.

Eat-stop-eat – Fast for 24 hours once or twice a week.

Alternate Day Fasting – Fast every other day.

Random Meal Skipping – Randomly skip meals throughout the week.

Time Restricted Eating – Eat daily within an 8-12 hour window.

Fasting in itself is an interesting topic and intermittent fasting is just consistently adding in fasting to your diet protocol, but can be implemented in many different ways.  Some claim fasting improves metabolism, insulin resistance, increases testosterone and growth hormone, increased muscle mass, improves weight loss, and can lead to life extension.  Now, you must keep in mind that nutrition science is hard, I say it a lot, but it is hard to control for all the variables in people’s lives and track year after year exactly what people are eating, when, and other lifestyle factors.  The claim of life extension and weight loss may be due to the fact that it is simply harder to over-eat when you cut down on the hours spent eating.  It may be the case that eating the right amount of food at each meal will have similar benefits to intermittent fasting.  There are however a few claims that make a lot of sense to me: Fasting building up your body’s resiliency, an increase in Human Growth Hormone high until fast is broken, and the circadian rhythm of your enzymes and bodily functions that time restricted eating can account for. 

Resiliency - We should periodically be exposing our bodies to a wide variety of stresses that get us out of our comfort zone.  Certain stresses can actually turn on and off certain genes in our bodies.  Exposing ourselves to heat, cold, hunger, stress, sleep deprivation, etc. can have some very positive impacts on our bodies ability to adapt to circumstances and our overall health.  If we get HANGRY when our eating schedule is not perfect, then we could greatly benefit from some intermittent fasting, so food does not have so much control over our moods.  Our hunger hormones should provide us information, not control our moods.

Circadian rhythm of enzymes – This is the aspect of fasting that interests me the most.  It has been shown that once we eat the first thing each day, it sets of a series of processes in our bodies that prep us for digesting and using food for the day.  These processes usually run efficiently for up to 12 hours.  So, if you wake up and eat breakfast at 7 AM, then your body is efficient at digesting food until 7 PM.  Anything eaten outside of that 12 hour window, even good food, will not be processed as well as it would have been earlier in the day.  It also appears that a 10 hour window is better than 12 and an 8 hour window is yet better. 

It also looks like Human Growth Hormone (HGH) is elevated after sleep until you consume your first digestible food.  HGH helps repair and restore bodily tissues, so, it would make sense to me that you may recover better from workouts with extended periods of higher HGH levels.  Just because you have higher HGH levels fasted in the morning does not mean that it will actually be used for muscle and tissue repair, but it does sound possible.

So, how do I put this information into practice?

Since I am not trying to lose weight, I stick to Time Restricted Eating and starting my first meal later in the morning to take advantage of the longer elevated levels of HGH post-sleep.  I keep my meals within a 12 hour window, ideally closer to the 8-10 range.  I have yet to try it, but I am extremely interested in trying a 5 day fast.  I am hesitant because I don’t have a lot of body fat to lose and don’t want to lose muscle mass.  I’ve hear many claims saying I will not lose muscle mass, but I have not had the guts yet to try it out, so let me know if you have any experience with this or not.

Some things to remember:

Coffee/Tea breaks a no-food fast, but is OK if you are simply doing a food restricted fast.  Anything you digest does start your 12 hour clock though if you are sticking to time restricted eating!

Go about your normal day/life as usual.  Working out fasted is OK, and if it’s not, then we should reconsider how “good” fasting actually is for us.  

Don’t let it turn into an eating disorder.  It’s not an eat as much as possible in your eating window thing and it’s not a constantly starve yourself thing.  We need a healthy relationship with food and eating.

What should you do?

Don’t get too caught up in the weeds here unless you already eat a clean diet.  Eating real food, not too much, mostly vegetables, is vastly superior than any amount of fasting you are going to do.  If you’ve got a healthy diet down, then and only then, I would start with time restricted eating and shoot for an 8 – 10 hour window.  If things are going well, you can dabble in other techniques.