Intermittent Fasting and Muscle Building Theory

Hey GTS readers! Today I have a great guest blog post from the people over at the Eat, Stop, Eat blog.  Brad Pilon and his team have done a great job changing peoples lives with the power of intermittent fasting (IF). If you have been a follower of my blog, you already know that I am a big fan if IF.

One question I get from a lot of people is about IF and building muscle. So, I was excited to get this guest post up on my blog from Vit Kashchuk,, the editor of I hope this post can clear up some questions and give you some more clarity about the many benefits of intermittent fasting. Enjoy! eatstopeat

Fasting and Building Muscle 

Current research shows that short-term fasting is actually good for your muscles, thanks to increased growth hormone, cellular cleansing, and muscle protein synthesis. However, in this post you will not encounter any scientific findings on the subject. Instead, you’ll learn a simple yet unconventional theory that explains how it’s possible to gain muscle on a fasting diet and how the popular bodybuilding mantra “eat big to get big” can lead to weight gain.

First, let’s suppose that the “natural” state for your body is one of growth with a system of checks and balances that help prevent this constant growth. To frame it as an analogy, it’s like a having a car with the accelerator permanently stuck to the floor, and you have to regulate the sped of the gar by pushing down or releasing the brake. However, in the case of your body, there are dozens – if not hundreds – of brakes.

So, according to this theory, the body’s natural state is one of growth; therefore, you don’t need to “force” growth through eating massive amounts of food, as growth is the default setting. Rather, if growth is what you desire, what you need to do is examine the “brakes” in place that prevent growth. Remember that these “brakes” are not a negative; after all, uncontrolled growth is nothing something we would ever want!

These brakes are both intrinsic and extrinsic, meaning they can come from within your own body (such as the myostatin gene which prevents muscle growth) or from external sources (such as not working out or having excessive amounts of inflammation in the body). This is far different than the current accepted theory, which is that in adulthood the body simply stops growing and must be prodded, stimulated, and forced in order to grow further.

This theory explains the inconsistency of guidelines such as protein or calorie intake for muscle building, as well as the inconsistency of results. In our theory, a nutrient deficiency can function as a “brake” to muscle growth. However, once that “brake” is removed and you start taking in adequate amounts of protein or calories, then adding more food and nutrients would do nothing to spur more muscle growth. After all, once a brake is off, it’s off – it can’t be “more off!”

That is why muscle growth is possible with intermittent fasting. As long as you consume an adequate level of protein that calories in order to support muscle growth, and allow for muscle growth with appropriate resistance training, your muscles will grow.

As for the question of “what is adequate,” this depends entirely on the person. For example, a 5’2” woman who has a sedentary lifestyle aside from 3-4 workouts per week may be able to lose fat and build muscle on a 1,200-1,500 calorie per day diet. However, a 6’2” man who exercises for 2-3 hours per day and expends a great deal of calories at work may not be able to build muscle at 4,000 or even 5,000 calories per day.

Remember, “adequate” for muscle growth doesn’t necessarily correlate to maintaining body weight. “Adequate” levels of protein and calories relate more to the size of the “deficit” and “reserve” than one hard and fast number. It will take some trial and error to find the right number to suit your body and your desired results.

Also, it is important to understand that this number can change as your life changes. For example, if the 5’2” woman in the example above suddenly increases her daily activity level, it is likely that 1,500 calories will no longer be sufficient. Similarly, if our 6’2” man suddenly reduces his exercise to only 1 hour per day, then his previous 4,000-5,000 calorie intake may be enough to make him become severely overweight in only a couple months.

The bottom line is that building muscle combined with intermittent fasting is completely possible. A short-term deficit of calories does not seem to affect long-term processes such as muscle growth, and “adequacy” for muscle growth does not necessarily correlate to “maintenance” for body weight.

Also, the exact amount of calories or protein you need changes along with your lifestyle and activity levels. Therefore, a giant surplus of calories is not the answer to muscle growth. The more honest answer is that aiming for “adequacy” is far better for your health and desired results. However, this is trickier to pinpoint than most experts will let on, which is why this theory has not become as popular the conventional “eat big to get big” mantra despite its potential for greater success.


This post was contributed by Vit Kashchuk, personal trainer, intermittent fasting fan and editor of

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