Layoffs from training are an inconvenience, whether it be due illness, injury, or other circumstances (gym closures, etc.).
Whenever an individual is faced with a layoff from the gym, a natural concern is losing their hard-earned progress and potentially losing muscle.
But, how long does it take to lose muscle?
Does missing just a single workout (or post workout protein shake) cause you to start losing muscle, or does it happen after a couple of days, a week or two of missed workouts?
We’ll answer that very question next, but first, let’s discuss some of the factors that can affect how fast you may lose muscle when you can’t / don’t train.
Factors Affecting Muscle Loss
Age
Unfortunately, the human body isn’t like a fine wine, meaning it doesn’t always get better with age. After a certain point, things start to decline, including collagen production, hormone synthesis, and how effectively your body builds and retains muscle.
As with most things in life, the older we get the harder it is to hold onto certain things, including muscle.
Part of the reason is that the body isn’t as efficient at building proteins. Another part is that there is an element of natural motor neuron degradation, which makes it more difficult to recruit muscle fibers.
If muscle fibers aren’t stimulated frequently, they begin to break down and shrink.
Consistent resistance training helps attenuate this decline allowing you to keep more of your muscle as you age.
Sex
Men naturally have higher levels of anabolic hormones, like testosterone, which may make it easier for them to hold onto muscle during times of inactivity. Regardless of hormone levels, though, if you go for long enough without training, you will lose muscle.
Nutrition
The importance of nutrition can’t be emphasized enough, especially when it comes to retaining muscle mass. Protein intake is crucial as it provides the essential amino acids the body needs to build, repair, and maintain muscle mass. If you’re not consuming enough protein, even if you are training, you risk losing muscle mass.
This is why it’s important to consume enough protein each day from quality sources like beef, chicken, eggs, fish, and/or whey protein.
Protein intake recommendations for those looking to optimize body composition and build/maintain muscle are between 1.6-2.2 grams of protein per kilogram of bodyweight, which comes to ~0.8-1 gram of protein per pound of bodyweight.
Training Experience
The longer you’ve been training consistently, the more muscle you likely have (provided you’ve been training and eating properly, that is).
Moreover, the longer you have been training and the more muscle you have, the less likely you are to lose muscle as quickly as someone who hasn’t been training as long and subsequently takes a layoff from the iron.
This is on account of muscle memory.
When you build muscle, more nuclei enter the cell. When you take a break from training, the size of your muscle may decrease, but the nuclei do not disappear. This is why it’s easier to rebuild muscle that’s been “lost” rather than build new muscle tissue.
Now that we’ve reviewed the factors impacting how fast muscle loss can occur, let’s answer the question..
How Long Does it Take to Lose Muscle Mass?
Fortunately, to answer this question, we don’t have to speculate or postulate. We have hard research conducted in healthy human beings experienced with resistance training.
A 2017 study took resistance trained men and had them follow and upper/lower split for four weeks.[1] After which, the men stopped training for two weeks.
Researchers then took ultrasound scans of the men’s quadriceps and compared it to previous scans taken during their weeks of resistance training.[1]
They noticed that the men did NOT lose any muscle, nor did they lose any of their strength after the two week break from training.[1]
A previous study from 2015 found that losses in upper body muscle mass occur after about three weeks of not training.[2]
An earlier 2012 study had subjects either train consistently for 24 weeks (6 months) or perform three cycles of 6-week training intersperse with 3-week detraining periods between each 6-week training cycles.[5]
Researchers noted that the detraining group did lose some muscle in their triceps during both of the three-week layoffs, 2.6% and 2.9%, respectively.[5]
However, the detraining group quickly regained their muscle mass and size when they returned to training, keeping them on pace with the group that did not take 3 week breaks from training.
By the end of the 6-month study, both groups made similar gains in size and strength, even though one group (detraining group) did 25% less training![5]
Smaller Muscles Don’t Necessarily Mean Muscle Loss
Now, something to keep in mind that just because a muscle has decreased in size doesn’t necessarily mean you’ve actually lost muscle mass.
You see, muscle isn’t just made of protein. It also contains water, fat, and glycogen (the stored form of carbs in muscle).
Taking a break from training leads to a reduction in the amount of glycogen stored inside your muscles.[3]
Furthermore, when glycogen is stored in muscle tissue, it also stores some water, which means that any loss in glycogen will also mean there’s a decrease in how much water is in the muscle.
This is why after a week or two of detraining your muscles will look smaller -- they’re holding less carbohydrate and water[4], but that doesn’t necessarily mean you’ve lost actual muscle protein.
As soon as you start training again, water and glycogen stores will return to their normal levels and your muscles will be just as full and round as before.
Takeaway
A number of factors will impact how fast you lose muscle mass when you take a break from training, including age, training experience, gender, and diet.
Research to date shows that muscle loss begins to occur around the 2-3 week mark.
The good news is that even though you may lose muscle when you can’t get to the gym for a couple of weeks, the data indicates that you’ll regain it very quickly so that you’ll be back at your normal size in no time!
References
- Hwang PS, Andre TL, McKinley-Barnard SK, Morales Marroquín FE, Gann JJ, Song JJ, Willoughby DS. Resistance Training-Induced Elevations in Muscular Strength in Trained Men Are Maintained After 2 Weeks of Detraining and Not Differentially Affected by Whey Protein Supplementation. J Strength Cond Res. 2017 Apr;31(4):869-881. doi: 10.1519/JSC.0000000000001807. PMID: 28328712.
- Yasuda T, Loenneke JP, Ogasawara R, Abe T. Effects of short-term detraining following blood flow restricted low-intensity training on muscle size and strength. Clin Physiol Funct Imaging. 2015 Jan;35(1):71-5. doi: 10.1111/cpf.12165. Epub 2014 May 14. PMID: 24828574.
- Mujika I, Padilla S. Detraining: loss of training-induced physiological and performance adaptations. Part I: short term insufficient training stimulus. Sports Med. 2000 Aug;30(2):79-87. doi: 10.2165/00007256-200030020-00002. PMID: 10966148.
- Nygren AT, Karlsson M, Norman B, Kaijser L. Effect of glycogen loading on skeletal muscle cross-sectional area and T2 relaxation time. Acta Physiol Scand. 2001 Dec;173(4):385-90. doi: 10.1046/j.1365-201X.2001.00913.x. PMID: 11903130.
- Ogasawara R, Yasuda T, Ishii N, Abe T. Comparison of muscle hypertrophy following 6-month of continuous and periodic strength training. Eur J Appl Physiol. 2013 Apr;113(4):975-85. doi: 10.1007/s00421-012-2511-9. Epub 2012 Oct 6. PMID: 23053130.
