I completely understand anyone thinking, “Will I Lose Muscle if I Run in the Morning?”
What I mean is that you’ll typically train with weights to build muscle and then perform cardio to keep body fat to a minimum.
So, an excess of cardio, or performing cardio first thing in the morning on an empty stomach, seems as though it works against muscle-building principles.
With that being said, the last thing you want is for your hard-earned muscle to be covered in layers of fat.
So, what should you do?
Allow me to explain what you need to know about losing muscle and running in the morning.
Will I Lose Muscle if I Run in the Morning?
You won’t lose muscle if you run in the morning, although this does depend on both the intensity and length of your run. Your workouts are typically fuelled by stored glycogen in the liver and muscles. Once your glycogen stores are depleted the body will turn to burning fat for energy. However, a longer or more intense run may cause your body to breakdown amino acids for energy, which is when you can potentially lose muscle.
1. The Truth About Cardio & Muscle Loss
I’ll openly admit that I’m not a fan of “traditional cardio”.
However, in reality, this is simply because of how most people choose to perform cardio.
If your aim is to produce as much muscle mass as possible you’ll generally find that either really low-intensity or very high-intensity cardio are your best options.
So, as is the case with many pro-bodybuilders, very low-intensity cardio will typically involve a long, but easy-paced session.
A great example of this is walking for 45 minutes or using an elliptical trainer at the lowest resistance levels with a slow pace for 30 minutes.
When I talk of high-intensity, this generally involves a short, sharp, and fast-paced workout.
So, as an example, 10 minutes of non-stop burpees and bodyweight squats.
With that being said, the main issue I have is that most people tend to perform mid-to-long bouts of moderate-intensity cardio, e.g. 45-90 minutes of jogging.
Unfortunately, it is these slightly longer, moderate-intensity cardio sessions that can potentially lead to muscle loss.
I’m definitely not saying that this is always the case, but it can happen.
Realistically, to gain or maintain muscle mass comes down to the type of exercise you’re performing and how many calories you’re consuming compared to how many you’re burning.
If you’re burning more calories than you’re consuming then it becomes more difficult to maintain or build muscle mass.
Once more, it’s definitely not impossible to build muscle, but definitely much harder.
However, running can be a cause for muscle loss in some circumstances, and I’ll cover those now.
2. Will You Lose Muscle if You Run on an Empty Stomach?
I would hazard a guess that this is what you really want to know.
Basically, will running or performing cardio first thing in the morning on an empty stomach lead to muscle loss?
The best way to answer this is to look at how your body actually fuels that early morning, fasted run.
Whenever you eat your body will store glucose (sugar) in the form of glycogen.
This glycogen will usually come from the carbohydrates that you eat.
Plus, glycogen is stored in your liver and muscles to be used for energy at a later time.
Now, once you’ve had your evening meal your glycogen stores will be pretty full, although the body only has the ability to store so much glycogen at any one time.
However, you are still using energy, even when you’re not doing anything.
Breathing, your vital organs functioning, sitting down, standing up, lying down, etc. all require energy.
So, you could also say that you’re using energy while you’re asleep.
This will automatically decrease your glycogen stores, which means that you’ll have less fuel for energy the following morning.
However, in most cases, you should have enough stored energy (glycogen) to fuel a 30-40 minute workout.
With that being said, this will depend on the type of workout and how intense you’re looking to go.
So, in effect, if you’re running 3-4 miles in the morning on an empty stomach you shouldn’t experience any muscle loss.
However, as your workout continues you still require energy to fuel this, and the body has to find this from somewhere.
So, once your glycogen stores are depleted the body will use stores of fat for energy.
And the body’s next port of call for energy will be protein, more specifically amino acids.
If you allow your body to get to the stage where it requires amino acids for energy, this is when running could potentially cause you to lose muscle.
3. Running Could Be the Worst Cardio For Muscle Retention
Okay, so we’ve established that you won’t specifically lose muscle from running in the morning, but there are a few caveats.
As I’ve mentioned, keeping your calories consumed equal to or higher than your calories burned is the ideal way to maintain or build muscle.
Plus, ensuring that your run is fuelled by glycogen or body fat is great, using amino acids for energy is terrible.
Basically, whenever you exercise, running or otherwise, your muscles are “damaged” or broken down.
This is absolutely fine, as adequate nutrition, rest and recovery will allow the muscles to grow back, typically bigger and stronger.
However, when it comes to cardio, unfortunately running may not be the best option.
In order to build muscle you must stress and stimulate that muscles in a certain way, and unfortunately moderate-intensity running (jogging) doesn’t really provide this.
If you think about it, a cardio session on the stationary bike or stair climber leaves your quads and glutes literally burning.
This can best be described as metabolic stimulation of the lower body muscles.
So, in effect, the same type of lower body stimulation that is typically felt when you lift weights.
However, you very rarely feel the “burn” when you’re running.
In fact, when using the stationary bike and stair climber it’s likely that your legs will give out before your heart.
If you think about it, this is exactly the same as when you perform a few sets of squats.
Yes, you may be breathing hard, perhaps even sweating, but it’s your legs that scream, “No more, let me rest” and not your heart.
However, running is the complete opposite, more of a full-body cardiovascular exercise.
Therefore, you’ll generally stop running once your heart (breathing) can’t take it anymore.
But, you definitely won’t have that same burning sensation in the legs that you get from the bike, StairMaster, or squats.
So, in effect, biking and stair climbing is stimulating your muscles in a similar way to when you train them for growth.
With that being said, there are forms of running which provide this muscular stimulation.
4. Some Forms of Running Can Build Muscle
So, as I say, there are actually certain forms of running which may help you build muscle.
The most obvious of these is sprint workouts.
Sprinting can be considered high-intensity simply because it’s taxing on the Central Nervous System and it’s not something you can do indefinitely.
Plus, sprinting raises your metabolic rate in much the same way as weight training does.
Furthermore, going back to the comparison between running and cycling, and the “quad burn”, you’re much more likely to “feel” your muscles when sprinting.
I would also suggest that if you go running in the morning that you actually “run”, as opposed to jogging.
Once more, this is a higher intensity workout and an activity which you’re unlikely to be able to keep up for an extended period.
Finally, if maintaining muscle is more important to you then you may be better off avoiding running first thing in the morning.
Basically, do the type of training that is most important to you first (weight training to build or maintain muscle).
The reason for this is that your “main” workout will leave you feeling slightly fatigued, so you may not be able to perform your second workout with as much intensity.
However, maintaining or building muscle will always be about consuming the same or more calories than you’re burning, while focusing on training which provides resistance for your muscles.
How I Balance Weightlifting & Running
So, I hope you understand that you potentially won’t lose muscle if you run in the morning (or on an empty stomach).
However, it’s important to remember that your body will initially use glycogen stores to fuel your run.
Once your glycogen stores are depleted the body will use fat stores for energy.
But, once your body starts using amino acids for energy you’re in danger of losing muscle.
With that being said, if you are consuming enough calories and performing the right type of resistance training (in addition to running) then you can maintain and even build muscle.
Are you ready for a new type of running? I’d like to introduce you to a form of running, which not only burns body fat, but also helps to build lean muscle mass. Interested? Then check out my Anabolic Running Review.
Hi, I’m Partha, the founder of My Bodyweight Exercises. I’m someone who’s been passionate about exercise and nutrition for more years than I care to remember. I’ve studied, researched, and honed my skills for a number of decades now. So, I’ve created this website to hopefully share my knowledge with you. Whether your goal is to lose weight, burn fat, get fitter, or build muscle and strength, I’ve got you covered.