What Does It Take To Deplete Your Glycogen Stores Quickly

March 24th 2020

You can enhance your training by optimizing what energy system your body uses.

By doing so, you can get results such as increased energy, decreased risk for developing chronic health conditions, or by being able to eat the foods you want without increased weight-gain or health risks.

There are reasons why certain people will want to deplete their glycogen storage which we will touch on later.

But the main question this article answers is how to deplete your glycogen stores quickly.

Before we answer the question, let’s go into detail what exactly glycogen is and what it does for the body.

What is glycogen, how is it stored, and what does it do?

Your body utilizes a variety of mechanisms in order to create energy.

Your body is constantly burning energy to allow you to move, think, breathe, etc.

When you are lifting, riding a bike, or doing any sort of activity, your body is burning a lot of energy in order to allow you to continue the activity and prevent you from burning out.

So, where does your body gets this energy? What fuels our bodies?

The answer is glycogen.

Glycogen is the stored form of glucose (carbohydrate) in our body.

Whenever you eat any form of carbohydrate (bread, wheat, rice, etc.) it is broken down into glucose and enters the bloodstream.

From there, it is either used up immediately (let’s say you went on a run after eating some oatmeal) or the excess is stored as glycogen which can be quickly broken down and used for later (for example, going on a run 2 hours after eating breakfast).

Glycogen is used primarily for high-intensity activities such as weightlifting or sprinting.

Glycogen is stored in each individual muscle, and in our liver.

When our body utilizes all the glycogen in our muscles, it will signal the liver to release glycogen which is transported through the bloodstream so that it goes to the muscle that is working.

The result is replenished energy which allows us to continue performing the activity at a high level.

To give a specific example, let’s say you are working your biceps doing the bicep curl.

While you are performing a curl, the glycogen that is stored in your biceps is being used up in order to give your muscles the energy it needs in order to contract and lift the weight.

After performing, let’s say 10 reps, your biceps start to run out of its stored glycogen. 

As a result, your muscle does not have the energy it needs to fully contract and lift the weight. 

This is known as muscular failure. 

At the same time, your body senses that your biceps have run out of energy and signals the liver to release its stored glycogen so that your biceps have more energy to continue curling.

This process takes time so you will most likely fail to lift the weight before your body starts to replenish the bicep’s “gas tank.”

When you are done with your set and are resting, you are giving your body the time it needs to release glycogen from the liver into the bloodstream to return to your biceps. 

This will help replenish the glycogen stores in your biceps and give you the energy to curl 10 reps during your next set.

What are the benefits and drawbacks of depleting your glycogen storage in regards to strength training?

Depleting your glycogen stores is a topic that is still being researched.

The main reason people cite as a reason for decreasing their glycogen stores is to utilize the other systems the body uses in order to get energy.

People primarily do this to lose more fat and overall body weight.

The glycogen system is just 1 out of 3 systems the body uses to get the energy it needs to perform activities.

The other systems involve using fat (fat from foods, not the same fat on your body), or protein for energy.

These two systems usually take a longer time than glycogen in replenishing your muscle’s energy, but you can train your body and augment these alternative systems so that they work faster and faster.

As stated before, glycogen is the primary system used for high-intensity exercises such as lifting or sprinting.

But if your body runs out of glycogen, it will start to use fat or protein as fuel for this energy.

The only reason why you would want to do this purposefully is if you are following a low-carb diet and primarily use fat as fuel or are following a carnivore diet and primarily use protein as fuel.

The drawbacks of depleting your glycogen stores are that until your body gets used to using the other systems, you have a lot less energy, and feel a lot more fatigued during high-intensity exercises.

It will take time for your body to adjust to utilizing the other energy systems as its primary system, and until it reaches that stage, you will feel a significant decrease in energy throughout the entire day.

Another drawback is that a lot of the research on the subject is mixed, meaning we do not know the consequences of primarily using fat or protein as energy as opposed to glycogen.

Glycogen is the main fuel source of humans for high-intensity exercises for centuries.

It was only recently that scientists found a correlation between glucose and chronic health conditions such as cancer, Alzheimer’s, and inflammation.

But if you ask me, overconsumption is a disease in itself and another topic to be discussed.



But even with this correlation, it does not necessarily mean that glucose is the cause of these diseases.

Some believe that glucose does play a role, and in order to maximize their health, they abstain from eating glucose and follow a low-fat diet.

There may or may not be health benefits to a low-fat diet, the evidence is not yet clear.

Another reason why someone would want to deplete their glycogen stores and optimize their body’s ability to burn fat is endurance athletes.

Fat takes a long time to be used as fuel, but it can supply more energy.

This is not ideal for high-intensity exercises which requires a lot of energy very quickly, which is what glycogen is optimized to do.

But for endurance athletes who are constantly running for hours on end, fat may be a better fuel source, if it is has been optimized.

But as stated before, this is just a theory and the literature on this subject is still mixed.

Nevertheless, there is sufficient evidence to show that depleting glycogen storage causes the body to utilize other energy systems which doing so over a long period of time, results in optimization.

How long does it take to deplete glycogen storage?

How long it takes to deplete your glycogen stores depends on the type of exercise you do, what parts are being worked, and the intensity of the exercise.

If you are doing full-body HITT workouts, going super hard, you could deplete your glycogen stores as fast as 20 minutes.

If you are doing low-moderate intensity exercises such as distance running, it might take you 90-120 minutes in order to fully deplete your glycogen stores.

Or, if you prefer not exercising, your body fully utilizes its glycogen stores in about 16-22 hours.

But keep in mind, during this time, you should not be eating anything with glucose in it. 

The key to depleting your glycogen stores quickly is to perform high-intensity exercises involving as many muscles as possible.

How long to deplete glycogen stores in a Carnivore diet? Low carb diet? Fasting?

If you are looking to deplete your glycogen stores in order to utilize the other energy systems in your body, how long it will take you to deplete your glycogen stores primarily depends on how much glucose you are currently getting in your diet.



There is glucose in most foods, if you are on a carnivore diet and add barbeque sauce to your meat, that is a source of glucose that you must use up first before your body can use protein as the main energy system.

If you are on a keto diet and have vegetables, there is some glucose in vegetables so you will have to burn that up first.

If you are fasting, it depends on how long you have been fasting for, and what your previous meal is.

There is no set guideline on how long it takes to deplete glycogen stores for these alternative diets. There are just too many variables involved.

This is something you will have to test and see for yourself, but as long as you are following these diets well and haven’t been cheating, it shouldn’t take very much time.

But as a general rule of thumb, fasting would take around 16-22 hours to completely deplete your glycogen stores.

And depending on what you eat during a low carb or carnivore diet, this will only delay that amount of time.

As stated earlier, you need to experiment and see what works best for you.

No advice on the internet could replace your trial and error and personal experience.




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