

Intermittent Fasting for Bodybuilding
Does It Really Work?

Kyle Newell
Published by Kyle Newell
Fact checked by Markus Oliver, BHSc FACT CHECKED
Last updated: January 8, 2021

Back in 2007, at the peak of my competition days, I won one of the two shows that I competed in, the South Jersey.

Interestingly enough, I got prepared for that show without having one single protein shake.  Yup, you read that correctly.

It was one of the many times that I experimented to see real-world results on myself.  Now, although this isn’t directly related to longer fasting, it showed me that I could get ripped and stay muscular without ingesting protein shake after protein shake and eating a bunch of animal meat.

One of the major concerns that people bring to me is that they are fearful of losing muscle or not being able to gain muscle while fasting.

Let me address the issue of the fear of losing muscle first.

Exercise And Intermittent Fasting

fasting while working out

Remember how I said that everything our body and brains do are done with survival as the ‘main thing’?

Well, go back thousands of years, just imagine, you were to wake up in the winter one morning and animals were scarce and plants were mostly dead or ‘sleeping’.

This would obviously mean that food would have been hard to come by.  Which meant you would have had to go out and hunt and search for it, sometimes for days.

I don’t think anyone can really debate this logic.

Well, your brain, which sends the messages to your body, came up with great ways to deal with this.

The first thing has to do with movement.  If we received the message when we were trying to gather food for actual survival that we didn’t like to walk for miles and actually ‘get after it’, we would have thrown in the towel and our chances for survival would have gone down significantly.

This means that movement and exercise make us feel good.  There are certain growth factors and hormones that can only cross the blood-brain barrier via physical movement.

Physical movement is literally the quickest route to make us feel good and if you feel good, you are more likely to stick with your plan.

Which kind of ties into a quick point on exercise.  It is great for brain health, which is the most important thing about it in my opinion and it is great for overall vascular health/blood flow and gaining strength and building muscle.

But, I’ll be the first one to tell you that exercise is damn near useless for weight loss.  Yes, you read that right.

Ok, the second thing that is pretty awesome that our body does when it goes for a period of time without food is that it increases growth hormone dramatically (2000-3000%!) which is great for mobilizing fat stores and preserving muscle.

And in studies on overweight men, fasting has been shown to increase luteinizing hormone (LH) by up to 67% [1]. LH is the precursor for testosterone production.

In another study, fasting as long as 72 hours (regardless of whether the subjects were exercising) did not cause an increase in breakdown of muscle nor did it slow down muscle protein synthesis (the building of muscle) [2].

This means that not only is fasting very muscle preserving, but if set up right, it could actually help you build muscle easier!!!

How Intermittent Fasting Works


Something I knew from my years of learning and being Coached while bodybuilding was that the more insulin sensitive a person is, the easier it is for them to put on muscle.

One of the main things fasting will do is make you more insulin sensitive and on the flip side, if you are overweight, it will help to heal your insulin resistance.

A note about insulin resistance: I want to use strength training as an analogy here.  What happens when we train with progressive resistance training?

Our muscles respond by becoming a bit bigger and stronger.

If we continue to train with progressive increasing resistance, we become bigger and stronger and so forth.

Your body has this response because it wants to be able to resist the heavier loads.

Your body becomes resistant to anything that it is exposed to in high doses.

We become insulin resistant when are constantly exposed to frequent feedings and are constantly eating refined foods.

Something that I have seen very few others talk about is this idea that when we set up an optimal internal environment by being more insulin sensitive is the concept of calorie partitioning.

Simply put, if you are more insulin sensitive, the calories you eat are less likely to be stored as body fat (without going too deep into this).

In a normal person eating a normal diet, let's say 50% of what they eat gets stored as fat and the rest goes to other systems of the body.  In the genetically elite, more of the food goes to the muscle.  These are the people that you can look at and envy because they are always muscular and lean, despite what they eat

This is something that I saw in full force while working with the Rutgers Football strength and conditioning program fresh out of college.  Many of these guys went on to play in the NFL so we know they were the upper echelon of the gene pool.

Let me just say that a stick of butter and a cup of brown sugar in their oatmeal wasn’t all that uncommon on a dude with an eight pack!

The last thing I will say about eating and putting on muscle is that if all else is spoken for, then it's really about the number of calories coming in for building new tissue rather than the amount of protein.

Here’s a note though about putting on muscle, because people always love to ask these questions about diet and protein and packing on muscle: The key to putting on muscle is not diet.

It’s resistance training! You need to stress the hormonal and muscular system enough that your body gets the signal (those damn signals again, but remember all the signals of your body are brought about via hormones).


Training with weights or some form of resistance is the main foundation for putting on muscle.

After that, you need to make sure you are setting up the proper hormonal environment for when the building blocks aka food, comes into the system.

If you have any questions about bodybuilding and fasting, please feel free to reach out at kyle@kylenewell.com.


  1. https://eje.bioscientifica.com/view/journals/eje/121/5/acta_121_5_020.xml
  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4096723/

About the author