What Is Muscle Catabolism? (And How To Avoid It)

Now we know that each individual’s goal is different, but often the answer to this question can be answered by one, or all, of the following: to increase our muscle mass, improve our muscle strength, lose fat, and ultimately become a better versions of ourselves.

And this process usually includes making drastic changes to our diet, in conjunction with a frequent and vigorous exercise regime.

But what if we are doing actually doing a little too much?

Exercising too frequently? Or making too large changes in diet?

Sounds impossible right? Well, maybe not.

You see, too much of a good thing (or in this situation, ‘good things’) is not always a good thing.


What Is Muscle Catabolism

What Is Muscle Catabolism?

If we break it down, catabolism simply refers to the breakdown of substances or molecules into smaller, simpler substances or molecules.

When used in reference to the human body, the term catabolism refers to the breakdown of specific molecules to maintain the efficient functioning of our various essential bodily processes.

A simple example is the breakdown of glucose molecules to provide energy to the tissue. Another could be the breakdown of carbohydrates in the gut to provide glycogen to the muscle tissue.

There are thousands of catabolic processes that occur in the human body that are important to the maintenance of our health. This breakdown of one substance so it can be used to build another, often more important, substance is integral to the healthy function of our body.

So What About Muscle Catabolism?

What Is Muscle Catabolism

Muscle catabolism describes the process where muscle tissue is broken down into smaller molecules called amino acids. These amino acids are structural protein molecules that make up various components of our cells.

Now while this process does ensure that our cells are kept healthy and functioning efficiently, it does come at the cost of maintaining lean muscle tissue. This is obviously not ideal if our personal training goals include increasing muscle mass, improving muscle strength, increasing aerobic fitness, or losing fat.

Unfortunately, muscle catabolism is actually most likely to occur in those of us who have the best intentions.

You see, muscle catabolism will happen under two very different scenarios.

Firstly, muscle catabolism will occur if our physical demands exceed our recovery requirements.

Each time we exercise, we place the body under stress. This includes causing damage to our muscle tissue and cells.

In an ideal scenario, these damaged tissues will be rebuilt bigger and stronger than they were before. But to be rebuilt stronger we need to ensure two very important things.

We need to ensure that we give the body enough time to recover fully.

And we need to ensure that the body has enough amino acids readily available to actually rebuild the damaged muscle tissue.

If we do not give the body enough time to recover by commencing vigorous or intense exercise too soon after a training session, we will cause accumulative damage to muscle cells and muscle tissue, leading to damage, muscle catabolism, and insufficient repair.

Additionally, if we don’t physically eat enough food, we will not provide the body with sufficient nutrients to actually repair the damaged cells, irrespective of how much time it is given to recover. In this scenario, we will breakdown muscle tissue to provide essential amino acids to damaged cells, as their repair takes priority over muscle tissue.

This is bad, as insufficient recovery and its resulting muscle catabolism will not only limit our ability to reach our personal training goals, it can also lead to injury, feelings of fatigue, lethargy, and even illness.

Secondly, muscle catabolism will occur if we do not create a demand to maintain muscle tissue.

Put simply, if we do not use our muscles, we lose our muscles. AKA muscle catabolism

This can occur due to prolonged inactivity, such as bed rest during late stage pregnancy, severe illness, or severe injury. Additionally, it can also occur (albeit much slower) as a direct result from sedentary lifestyle choices, AKA lack of exercise.

During this scenario, we do not use our muscle tissue, which suggests to the body that it is not needed. It is then broken down to provide nutrients and amino acids to those cells are involved in essential bodily functioning.

So What Is Muscle Catabolism?

Put simply, it’s the breakdown of muscle tissue due to insufficient recovery.

So now we know what muscle catabolism is, but what can we do to limit it?

How To Stop Muscle Catabolism

As mentioned above, there are two key scenarios that promote to muscle catabolism.

  • Insufficient physical activity (or too much sedentary activity, however you prefer to look at it)
  • Insufficient recovery from physical activity.

Within these two scenarios we can then draw three key factors that directly contribute to muscle catabolism.

  • Insufficient exercise
  • Insufficient recovery from exercise
  • Poor dietary choices.

So it would then make sense that the best way to limit muscle catabolism would be to address these three key factors.

Physical Activity

What Is Muscle Catabolism

Maintaining a physically active lifestyle can go a long way towards stopping muscle catabolism.


If we ONLY stick to long distance, endurance based exercise we will not reduce muscle catabolism as much as we possibly can.

You see, to truly limit muscle catabolism through physical activity, we need to create demand for muscle tissue.

This demand is created through resistance training (AKA lifting weights).

By lifting weights, we significantly stress the muscle tissue we currently have. This lets the body know that this tissue is important, and creates a demand to keep it.

As a bonus, weight training is also the most effective way to increase our muscle tissue, which can help improve strength and performance, and help promote greater rates of fat loss.

Physical recovery

What Is Muscle Catabolism

So we now undertake resistance training regularly.

This is awesome. We create a demand for muscle tissue while also promoting muscle growth.

So we do more of it.

And then even more of it

And before we know it, we are training balls to the wall 7 days per week.

This is not so awesome.

When we lift weights we create tissue damage. The repair to this damage is essential to muscle growth and recovery, and the changes in body composition associated. But by weight training too often we do not allow the tissue to recover fully. This leads to the continual breakdown of muscle tissue, leading to excessive muscle catabolism.

To avoid this, we should allow 48-72 hours recovery between heavy weight training sessions per muscle group.

So an example of this may look like this if we are using a full body weight training workout:

  • Monday: Heavy Full Body Session
  • Tuesday: Rest
  • ​Wednesday : Light Full Body Session
  • ​Thursday: Rest
  • ​Friday: Heavy Full Body Session
  • Saturday: Rest
  • Sunday: Rest

Or like this if we are using an upper body lower body split:

  • Monday: Lower Body Session
  • Tuesday: Upper Body Session
  • ​Wednesday: Rest
  • ​Thursday: Lower Body Session
  • ​Friday: Upper Body Session
  • ​Saturday: Rest
  • ​Sunday: Rest
What Is Muscle Catabolism

So by making smart training choices we can promote muscle growth and demand for muscle tissue without create excessive muscle catabolism.


what is muscle catabolism

So now we are training smart and ensuring we have enough time to recover from each individual workout.

Unfortunately, this means very little if we are not eating the required nutrients to promote repair of the damaged muscle tissue.

To promote repair of our muscle tissue, we need to ensure we have amino acids readily available in the blood around the times we workout. These amino acids are the building blocks of our muscle tissue, and are integral to promoting muscle growth and recovery, and limiting muscle catabolism.

Amino acids are what make up the macronutrient protein, so by eating adequate protein both throughout the day and around our training sessions, we can ensure amino acids are readily available for recovery.

We normally recommend eating 20-30 grams of protein 2-3 hours before your training session, and then another 20-30 grams within 1 hour after your training session. This will ensure you have amino acids readily available to promote recovery of the muscle tissue, and eliminate the risk of muscle catabolism.

So To Summarize

  • Muscle catabolism is the breakdown of muscle tissue into amino acids due to insufficient recovery, or prolonged inactivity.
  • Muscle catabolism can be reduced by weight training in conjunction with proper physical recovery and the correct nutrition.
Luke Cafferty

Luke Cafferty is a fitness junkie, personal trainer and blogger. He's passionate about living a healthy lifestyle and maintaining a strong and well rounded physique, while inspiring you to do the same.

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