This is a two part article series on intermittent fasting. If you haven’t done so yet, please take a few minutes to read Part 1 of the guide here. You’ll be happy you did.
Recall from Part 1 that intermittent fasting is the act of willingly abstaining from some or all food (and in some cases drink) for a period of time.
But how long is this ‘period of time’?
Well, it depends.
It depends on the fasting protocol you choose to follow.
Let’s dig into some details again…
Types of Intermittent Fasting Protocols
Remember that fasting is all about caloric abstinence for a set period of time.
So it’s time to decide what this time period is.
Here is a quick primer on some of the most popular fasting protocols.
Single 24 Hour Fast – This is the protocol advocated by Brad Pilon in Eat Stop Eat. For one 24 hour period a week, you fast. But this doesn’t mean that you have to avoid eating the entire day. You can choose your 24 hours to fit your schedule. This can mean starting your fast after dinner and fasting until the following evening (i.e. 6pm – 6pm). Or you can go morning to morning (i.e. 7:30am – 7:30am). Either way, the idea is to fast for 24 hours straight.
Condensed Eating Window – This is one of the most popular fasting protocols. The idea is to condense your food consumption period to a set number of hours, often between four to eight hours. This is your window of time where you can eat. The rest of the day (and night) you fast. This window can be changed to meet your schedule. As an example, Martin Berkhan from Leangains.com advocates an 8 hour eating window (usually from 1pm to 9pm) and a 16 hour fasting window.
Early and Late Fast – This is a variation of the condensed eating window protocol where you only allow yourself to get your food intake from two meals: one early in the morning and another late afternoon/early evening.
Skipped Meals – This is probably the easiest protocol to follow or introduce into your routine. Instead of following a set out routine and blindly consuming food every few hours, try listening to your body instead. If you’re hungry, eat. If you’re not, skip the meal.
Alternating Day Fast – This is one of the toughest protocols to follow as it requires you to go calorie free every other day for a set period of time (typically a weak). This style of fasting is usually associated with a level of ‘cleansing’ of the body. This is for the extreme.
How Fasting Affects your Metabolism
This topic has been beaten to death all over the Internet, so I’ll do you a favor and spare you the details and just give you the quick rundown.
The story told in many diet books is always the same.
If you don’t eat, your metabolism will slow down to a crawl to preserve your energy sources.
Well, according to numerous studies and sources, this simply isn’t true.
In one study, scientists discovered that when they forced people to fast for three days (72 hours) straight, their metabolic rate didn’t budge.
Another study found that people who fasted every other day for a period of 22 days had no change in their resting metabolic rate.
Most importantly, various studies have shown that people who skipped breakfast, or people who ate two meals a day compared to seven meals a day experienced no change in metabolic rate.
[Note: these studies were pulled from Brad Pilon’s book Eat Stop Eat]
So, clearly, short term caloric abstinence has no effect on metabolism.
You can breathe now.
How Fasting Affects your Exercise
This area is very much up for debate.
Training in a completely fasted state is advocated by some and despised by others.
There is another group that kind of goes both ways, suggesting it is best to take BCAAs or whey protein directly before a workout, as it’s low caloric content does not have a big impact on the fast yet it provides the necessary amino acids for optimal protein synthesis.
Regardless of where you stand, here are some facts.
A study done back in 1987 found that a three-and-a-half day fast did not have a negative impact on short-burst, explosive exercises such as sprinting or lifting weights. It ALSO didn’t have a negative affect on typical aerobic training.
Eight young men were tested for strength, anaerobic capacity and aerobic endurance in a post absorptive state and after a 3.5 day fast. It was concluded that there are minimal impairments in physical performance parameters measured here as a result of a 3.5 day fast. [Source]
Remember this is a 84 hour fast!
There was another study done in 1988 that showed no change in performance of soldiers who were exercising until exhaustion after fasting for three and a half days.
According to Pilon, the only time fasting might have a negative impact on performance is during lengthy endurance events such as marathons and triathlons.
But get this…
Studies show that performing a long endurance activity in a fasted state burns more fat than when in a fed state. The negative impact is that your time until exhaustion decreases. You burn more fat, but can run less.
So if fat loss is your goal, going for a light run in a fasted state might be beneficial for you.
But what about muscle mass?
There is another rumor going around that fasting (or dieting in general) will result in breakdown and loss of muscle mass.
Once again, false.
But there is one caveat.
The fasting needs to be supplemented with resistance training.
“Research on men and women undertaking a very low calorie diet found that even with a 12 week long diet consisting of only 800 Calories and only 80 grams of protein per day, the people in the study were able to maintain their muscle mass as long as they were exercising with weights three times per week.” – Brad Pilon (Eat Stop Eat)
Numerous other studies have been conducted on the topic and they all show the same thing – as long as you are using your muscles (resistance training) regularly (2-3 times per week), fasting (or any sort of caloric restriction) will not cause your muscles to disappear.
Note: During my Visual Impact Phase 3 test (lost 15lbs), my caloric restriction was drastically reduced (roughly over 1,000 calories per day). After all the water weight disappeared, I noticed my muscles remained intact. They tightened up, but they didn’t appear to break down because of my low caloric intake.
How to get Started with Intermittent Fasting
So now that we have all this information out of the way, how do you get started?
My recommendation is simple: start slowly.
Remember that according to research the majority of us are constantly in the fed state – 20 hours a day to be exact. And we’ve been in this state for years. Decades even.
So you need to start slowly and introduce short periods of fasting into your routine.
Start with skipped meals.
More likely than not, your day revolves around food. You’re used to eating at certain times of the day. You’re used to eating a certain number of times per day. Sometimes you’re just grabbing food because you think you’re hungry, when in fact you’re eating out of habit.
Stop this. Instead, start to listen to your body.
If you’re hungry, eat. If you’re not, then skip that meal. Your body doesn’t need it. It doesn’t want it.
This will be a little weird at first, but as you learn how to listen to your body, you’ll see just effective this can be.
Once your body begins to adjust (you’ll be feeling better already), start to move to either the condensed window protocol, or the 24 hour fast protocol (you’ll probably have to try out both to see which works for you better).
Once again, listen to what your body is telling you. Pay attention to the subtle differences between the fed and fasted states. Pay attention to your alertness. Your focus. Your hunger cues.
And act accordingly.
Remember that fasting shouldn’t be forced. You should feel good about it. You should feel good for letting your body regain it’s fed-fasted balance. I know that for many it will be going against everything they’ve ever believed in about food consumption. It will be hard to get away from the eat-eat-eat mentality.
But give it a chance. Try it out and see how it works for you.
I know that for many it has become a lifestyle.
It might be for you as well.
Some Great Resources on Intermittent Fasting
I just want to finish off this two part article series by giving you a few more resources on intermittent fasting. As I mentioned in Part 1, there has been a lot of buzz around the topic of intermittent fasting in the past few years.
And with a lot of buzz comes a lot of hoopla and misinformation.
The following resources will give you some useful information on the topic.
Brad Pilon`s book Eat Stop Eat – As you’ve probably noticed, I’ve referenced this book many times within this article. That’s because it is absolutely packed with useful and scientifically-backed information on intermittent fasting. If you’re at all interested in introducing fasting into your life (particularly the 24 hour fasting protocol), this is a must read.
Martin Berkhan’s Leangains Guide – Martin has been a student and practioner of intermittent fasting for a long time. He’s a nutritional consultant and an expert in the condensed eating window fasting protocol. His website is packed with useful information so be sure to check it out.
Greg O’Gallagher’s website Kinobody.com – Greg is a fellow blogger who I love to follow. He is also an advocate of Martin Berkhan’s condensed window eating fasting protocol. Greg will help you fill in the gaps when it comes to training (particularly in the fasted state). If you’re interested in learning how to set up your training routine to get the best results from intermittent fasting, check out his sample routine here.
There you have it guys – your complete guide to intermittent fasting.
I really believe that there is more than enough information here for you to get you started (or at least interested) in intermittent fasting.
Keep in mind that I’m currently in the process of testing out a few of the fasting protocols for myself and that I’ll be posting my findings once it’s all said and done. Let’s just say that the past week of condensed window eating has been more than eye opening. Definitely some interesting stories to share so stay tuned.
If you’ve had any experience with intermittent fasting or are interested in trying it (but have doubts), please leave a comment in the comment section below.
Please remember that I’m not an expert in this so if there are things I’ve talked about that you know are inaccurate (either from sources or personal experiences), please let me know so I can make any updates accordingly.
Let’s make this the best (and most accurate) guide on intermittent fasting on the planet!