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Fact checked by Kirsten Yovino, CPT Brookbush InstituteFACT CHECKED
February 11, 2023
Ask any lifter what their worst gym-based fear is, and we guarantee concerns over losing muscle mass and strength are at the top of that list. In fact, the fear of losing muscle mass has sparked a whole host of theories regarding potential ways to lose muscle.
A few of our favorite theories include: Did you run for a long time? Hello, noodle arms. Didn't eat protein 30 minutes after your workout? Goodbye, muscular thighs. Went on vacation for a week and skipped the gym? Say sayonara to that muscle definition!
While losing your gains is a legitimate concern, the idea that you'll lose it through the mundane variables we just listed is highly unlikely. We're going to tackle this issue for good, so you can stop stressing over the little things that ultimately will not matter to your muscle-building goals.
There are a lot of nuances we need to address, but you'll be happy to hear that unless you're actively trying to lose muscle, shedding your hard-earned mass isn't as easy as it seems.
Table of Contents:
To talk about losing muscle mass, we first need to know what it is we're actually losing. Of course, everyone knows what muscle is, but do you really know what it is? This is important as knowing what muscle is built of helps us understand how we lose it.
Muscle tissue consists of bundles of muscle fibers known as fascicles, and these muscle fibers are composed of myofibrils. Inside these myofibrils are the sarcomeres, which contain the contractile units myosin and actin.
Myosin and actin are the contractile parts responsible for the pulling of a muscle. Within the sarcomere is a fluid called sarcoplasm, which holds the material within the muscle cell, as well as high amounts of glycogen and myoglobin.
Muscle hypertrophy is the process of our muscle tissue growing larger. Muscle growth can actually occur in two ways: through myofibrillar hypertrophy and sarcoplasmic hypertrophy.
Myofibrillar hypertrophy is when new myofibrils are added to the existing muscle fiber. As we just discussed, these myofibrils contain the actual contractile units, which means our muscles will actually see growth in both lean mass and in gaining muscular strength.
Sarcoplasmic hypertrophy is when fluid fills the sarcomere, meaning no contractile units are needed. This is the type of hypertrophy most often associated with bodybuilding.
Sarcoplasm is the cytoplasm of the muscle cells found in the muscle fiber, and when sarcoplasmic hypertrophy occurs, this liquid fills up and expands the muscle fiber. In effect, sarcoplasmic hypertrophy is like a balloon filling up with water. The material of the balloon isn't actually adding new material, but rather, the material inside is.
Human skeletal muscle growth occurs when a large stress is placed on it. However, to build muscle, the stress needs to be large enough to send a signal that triggers the anabolic pathway, so that it thinks we need more muscle mass.
Keep this in mind as we begin to discuss the process of losing muscle.
Our bodies don't want excess muscle mass that isn't being used as it's inefficient. The only time our bodies want the muscle to grow is if they believe there's a reason we need it. This is why you must place a greater and greater demand on muscles when you lift, such as what occurs when following progressive overload.
If the stress isn't large enough, you'll wind up simply maintaining muscle mass and not gaining new muscle. If there's no stress, your body will begin to do away with the muscle as there's no need to keep it.
To summarize, you will lose muscle mass when you stop being active.
We can't give you a clear-cut answer without more explanation, as there are a ton of factors to consider when answering this question. Have you stopped going to the gym? Are you trying not to lose muscle? Is your activity level changing? Are you an advanced lifter or a beginner?
Let's dig into these factors individually so we can thoroughly answer this question.
You can actually see a drop in muscle mass and strength (and eventually a rise in body fat and body weight) fairly quickly from the day you stop training.
Assuming you're still staying relatively active, apart from not going to the gym, you'll probably see about a 10% drop in muscle mass bulk in just two weeks. One study measured an 11% drop in muscle after just 10 days¹. However, this rate can vary, depending on how much activity you do. For example, if you are injured or are completely immobilized, you may experience noticeable muscle loss, up to 2 pounds of muscle in just 1 week².
On the other hand, if you were to stop lifting but were engaged in sports or activities that demanded high muscle activation (like rock climbing, sprinting, maintaining cardio fitness, or HIIT), you may not lose any muscle mass.
Advanced strength athletes will see a loss in their gains quicker as their body requires higher stimulation to maintain muscle mass and strength. Basically, the closer you are to your genetic potential, the easier it will be to see a drop.
A meta analysis from 2013 looked at the rate of decay in the strength of elite rugby and American football players³. They concluded that advanced athletes may be able to go up to 3 weeks maintaining their existing maximum strength levels, but decay rates will occur between weeks 5 and 13.
This means that after just 3 weeks of detraining, you will experience quicker loss in your adaptations, which will escalate the longer you go. However, it needs to be noted that this is for elite athletes who are highly trained.
For beginning strength athletes, a short-term stint of detraining won't cause much, if any, loss. In 2013, a study looked at two groups of athletes who were new to strength training⁴.
One group followed a consistent 24-week training protocol while another followed the same protocol; however, their protocol was broken up into a 6-week training/3-week detraining schedule, lasting 24 weeks.
The study concluded that there were no significant differences in training adaptations in the two groups, with both improving relatively the same. This means that even though one group took two 3-week breaks from training, they still gained just as much overall muscle as the group that trained 24 weeks straight.
Even if you do lose muscle, it may not be actual muscle you're losing. Alternatively, even if it is, it may be easier than you think to get back. In addition, sometimes "losing muscle" from not training is exactly what you want to happen.
We're going to run through three variables you need to understand when losing muscle. Don't worry. It's really not as bad as you think.
One thing to keep in mind is that when you "lose" muscle mass immediately after ending training, you might not actually be losing muscle. You're probably just deflated.
When we eat food, our body will either break compounds down into glucose, which can be used immediately, or glycogen, which is stored in your muscles (as well as the liver).
Therefore, when we eat, our muscles will blow up as they're full of muscle glycogen. This is why some bodybuilders will manipulate their carb intake before a show. It also provides an explanation for nights in which you eat a ton of pizza yet somehow wake up looking jacked the following day.
Interestingly, a study found that you could lose up to 20% of your muscle size in just a week purely from loss of muscle glycogen⁵. This is also one of the factors that play a role in what's been termed muscle memory.
The term "muscle memory" is thrown around a lot and sounds a bit like bro science. However, the phenomenon of muscle memory is very real.
As mentioned, one factor that is evident is a short-term loss of muscle mass. We just discussed the role muscle glycogen plays, and when you quit the gym for a month or so, you should be able to get your gains back as fast as you're able to refill them back up with glycogen.
A long-term mechanism also makes "muscle memory" a real thing. In fact, there are some studies that show you could regain muscle mass much quicker after not training for 15 years! To be clear, this doesn't mean you will get back to your original spot. It simply means that you can gain muscle quicker than if you had never trained before.
One of the long-term chronic adaptations of resistance training is that you can add myonuclei to the muscle from satellite cells6. It seems that you can retain these cells for a very long-time. In fact, there's a small debate about if we lose them after 15 years or if we ever actually lose them!
Muscle memory is, in fact, very real, and if you did lose muscle mass but wanted it back, you can certainly regain it much more quickly if you want to get back into it.
Sometimes it's good to stop training and experience some of these "drawbacks" as it can actually help move your training forward. Nothing good happens linearly forever, and as the saying goes; "Two steps forward, one step back."
Apart from the recovery aspect a deload week offers, we can actually increase our anabolic response to stimuli. When we train for longer periods of time, our body's anabolic response can be weakened and less responsive to stimuli. Basically, we don't grow as much, even with the stimulus.
However, after detraining, our body's anabolic response can be increased to higher levels, which can even result in more growth than if we never reloaded in the first place7.
So, we're going to assume that a large majority of people asking this question aren't ceasing from training. Perhaps you're not going to have access to a gym for a while, or maybe you're starting school and won't have a lot of time.
Whatever it is, the good news is that if you don't want to lose muscle, you don't need to do a lot.
A 2021 study examined what would happen to the fitness level of trained subjects if they had a minimal amount of training8. Participants trained only one set per exercise once a week. The routine consisted of large compound exercises, and the one caveat was that the participants trained with maximal intensity, and each set was performed until true failure.
The researchers tracked both muscle mass and muscle strength to see when they'd see a significant decrease. It took the participants a whopping 32 weeks, more than half a year, to see a meaningful drop!
In other words, it doesn't take really long to see muscle loss, but it takes just a small amount of training to keep it! Remember above, when we talked about how you gain muscle by tricking your body?
Well, it seems like when we take the muscle to actual failure, it's as if we're tricking it from leaving, saying, "No muscle, I need you. Don't go!"
Apart from hitting the gym hard once a week, there are a few other things you can do to help preserve muscle loss.
You read this right! Creatine helps preserve muscle mass too. To be clear, this means if you sit and do nothing, creatine is still able to help preserve the loss of muscle tissue.
Researchers understand what creatine does, its role in physiology, and how it improves physique and performance. However, how it preserves muscle mass, even when a limb is immobile, is not quite fully explained.
The most important thing we know is that it works, even when totally immobilized9. It can also slow atrophy and the natural muscle loss that occurs in the elderly. Creatine is an excellent supplement that can benefit almost anything muscle-related, including muscle loss. If you're interested in taking it, check out our article that highlights the best creatine supplements on the market!
Protein is the other nutrition factor that you can't skimp on just because you're not training.
Again, the mechanisms aren't fully understood, but we know that maintaining high protein intake can mitigate muscle loss. Figure out how much protein you need per day, and stay within that range as often as possible.
And if you're planning to be less active for a certain amount of time, a high-protein diet can cause you to feel fuller, potentially reducing your amount of fat gain during this time.
We're sure you've heard that being in a caloric deficit can increase the risk of muscle loss. This is why it's important to continue following a workout split during times when you're trying to lose weight.
When you work out, you're convincing your body that it needs the muscle, so it should find energy elsewhere. When you take this stimulus away, it's like opening yourself up as a buffet table. Your body can grab calories and amino acids from where it wants, including your muscle tissue. That's going to negatively impact your body composition.
Obviously, if you need to lose weight, this would not be the ideal time to stop your fitness routine.
Human skeletal muscle possesses unique attributes that allow it to grow and function to meet the demands placed on the body. Some of these amazing attributes allow it to remain during shorter periods of time of no training and enable it to grow back faster if it is lost.
And, the amount of training you need to maintain muscle mass is actually surprisingly small. This leads us to say that it doesn't really matter how long it takes.
To clarify, if you plan on just not going to the gym anymore, you are going to see a drop in muscle tissue. Whether it's a fast loss occurring in 2 weeks or slow muscle loss that takes 2 months to happen, you will be saying adios to your muscle.
However, if it's just a temporary period in your life, you could come back and surpass where you're at now. And remember, if you need to pull back on training but want to preserve your muscle mass, it takes one hard set to fail to keep it.
The point is, don't worry about how long it takes to lose muscle. Instead, think about how long it will be until you can get back to the gym.
You now know how long it takes to lose muscle, but do you know how long it takes to build? To learn more, check out our article: How Long Does It Take For Muscles to Grow?
Prepare to maximize your gains with our exclusive 12-week hypertrophy training program. Choose between a 4 or 5 day training split and gain 2-12 pounds of muscle over 90 days...
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