What happens to your body when you stop lifting weights? This is a common question a lot of folks are asking right now as the global pandemic has most people training in some limited capacity.
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Key Points:
- Research shows that we tend to lose muscle very quickly with complete bed rest – mostly due to suppressed muscle protein synthesis.
- Doing any kind of physical activity will maintain muscle much better than doing nothing.
- You can prevent muscle loss through training (even minimal bodyweight workouts) and diet (eating at maintenance calories and consuming sufficient protein).
- Even if you lose size, muscle memory will rebuild lost mass quickly.
Key Terms:
Detraining: When you stop training and lose gains
Training Volume: How much total work you’re doing in the gym. Usually approximated as the number of tough sets.
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I want to start with a real-life example of muscle loss. Matt H is a pro natural bodybuilder and client of world-renowned physique coach, Cliff Wilson. After being hospitalized with Crohn’s flare-up, Matt was forced to take a significant break from training.
He went from 200 lbs on the left, all the way down to 166 lbs on the right, at about the same body fat. This means he lost just about 35 pounds of pure muscle!
We’ll come back to Matt later, but at this point I think it’s reasonable to wonder exactly how long it takes to see this kind of muscle loss. Does it happen after a week? A month? A year? And, does it depend on if you did absolutely nothing, or just reduced the training workload? Well, luckily, science can help us answer all of these questions.
Breaking Down the Cause of Muscle Loss
Before we dig into those questions, it’s important to first understand that muscle loss is a complex process – an ongoing tug of war between muscle protein synthesis and muscle protein breakdown, where gradually, the muscle protein breakdown side starts to win.
[Hey, quick interruption here. One thing I’m struggling with this blog is knowing how much detail to include compared to my YouTube videos. I know that I definitely want more detail — but how much is too much, you know? I guess I’ll just have to wait to get some feedback from you all on that. Anyway, if you’re in the mood for some mechanism and theory, just keep reading. If you’re only here for the applied info, scroll down to “How Long Does It Take To Lose Muscle?”]
We can think of skeletal muscle as a big brick wall: muscle protein synthesis is the process of adding bricks to the wall, while muscle protein breakdown is the process of removing them. These two processes are always occurring, and regularly swap turns taking the lead as we alternate between a fed and a fasted state. When we’re in a fed state, we tend to be adding bricks to the wall (assuming we ate enough protein in that meal) and we tend to be removing bricks from the wall when we’re in a fasted state (~8 hours after the last meal was consumed).1
What really matters for muscle gain and muscle loss in the long term balance between these two opposing processes. This balance, which we’ll call net protein balance, determines whether we gain, lose, or maintain muscle mass. If muscle protein synthesis is greater than muscle protein breakdown for a sustained period of time, more bricks are added than removed, and the wall gets bigger. We call this, positive net protein balance. On the other hand, if muscle protein synthesis is less than muscle protein breakdown for a sustained period of time, more bricks are removed than added, and consequently, the wall gets smaller. We call this negative net protein balance.
While we know that muscle protein breakdown must exceed muscle protein synthesis for us to lose muscle, there are actually several different ways this can occur: 1) muscle protein synthesis can decrease, 2) muscle protein breakdown can increase, or 3) some combination of these two processes can occur simultaneously. Because feeding itself impacts protein metabolism, in order to figure out which of these three scenarios occurs when we stop lifting, we need to consider the impact of detraining on protein metabolism in both the fed state and the fasted state. Let’s start with the fasted state.
Gibson et al. (1987) was the first study to examine the effects of muscle disuse on muscle protein balance in the fasted state in humans.2 They had six men place one of their legs in a long-leg plaster cast and after five weeks, measured muscle protein synthesis and breakdown following a 12 hour overnight fast. They found that muscle protein synthesis had decreased by ~26% when compared to the non-immobilized leg, while muscle protein breakdown had remained unchanged.
[Hey, another quick interruption. I hope you’re enjoying the blog so far. I’m enjoying writing it! I just wanted to say that I’m happy you decided to go the “mechanism and theory” route and didn’t just jump to the applied stuff. If you’re actually reading this, I’d love it if you sent me a DM on Instagram saying “purple monkey dishwasher” so I know people are actually reading this part. Thanks!]
Since then, these same basic findings have been replicated many times in studies of prolonged muscle disuse (>10 days).3-6 What these studies find is that muscle protein breakdown will sometimes increase in the first two weeks, but then quickly return to baseline (i.e. to pre-disuse levels). Muscle protein synthesis, on the other hand, decreases in the early stages of disuse (somewhere in the first ~10 days) and then remains depressed.3 This implies that when we stop lifting, the majority of muscle loss in the fasted state is coming from “less bricks being added to the wall” rather than “more bricks being removed from the wall.” Of course, detraining could impact the wall differently, once we eat food. So let’s take a quick look at what the science says about muscle disuse in the fed state.
Glover et al. (2008) was the first study to examine the effects of muscle disuse on muscle protein balance in a fed state.6 They had twelve young, healthy participants wear a knee brace for 14 days in order to immobilize one of their legs. After this period of time, they infused amino acids using IV at both high and low doses and measured the muscle protein synthetic response in both the immobilized and non-immobilized leg.
Their results showed that four hours after amino acid infusion, muscle protein synthesis was, on average, 54% and 68% greater in the non-immobilized leg compared to the immobilized leg after the low and high doses, respectively. Just like in the fasted state, it appears that detraining is decreasing the amount of bricks being added (but not affecting the amount of bricks being removed) in the fed state as well.
This research collectively demonstrates that muscle disuse leads to what’s known as anabolic resistance, where the muscle protein synthetic response to feeding is less sensitive and at a lower capacity than normal. Not only does muscle protein synthesis decline more than normal in the fasted state, it also doesn’t rise as much in response to feeding.
As the authors of Glover et al. (2008) note, knowing this allows us to tailor strategies for preventing muscle loss to target the decline in muscle protein synthesis, as opposed to an increase in muscle protein breakdown, which doesn’t seem to occur.6 As we will see later in the article, the best tools we have to accomplish this are though resistance-based exercise and, to a lesser extent, nutrition.
Before we discuss these tools, let’s first consider how long it takes to lose muscle and at what rate we tend to lose it.
How Long Does It Take To Lose Muscle?
How quickly you lose muscle largely depends on exactly how little you’re doing physically. Scientific evidence tells us that if you don’t do any physical activity at all, unfortunately, you can lose a lot of muscle depressingly fast. One 2016 study from Dirks and colleagues found that complete bed rest caused significant muscle loss in just one week.7 However, this type of study is likely not relevant to many of you, since these subjects weren’t regularly weight training in the first place, and unless you’re seriously injured or hospitalized, chances are you won’t be restricted to a bed for seven days including “hygiene and sanitary activities”.
Even if you’re not training at all, chances are, most of you will still be getting out of bed and doing some sort of normal everyday activity. And, as it turns out, just walking around is actually quite a lot better at preventing muscle loss than lying in bed all day, even if you aren’t actually lifting weights.
This was evidenced in a recent study from Hwang and colleagues.8 They took 20 subjects with at least one year of training experience and had them stop lifting all together for two weeks but still continue their regular daily activities (not complete bed rest this time). And, as you can see in the graph below, this time there was actually NO significant drop off in muscle mass after two weeks of detraining.
Notice how RT (4 weeks of training) and DT (2 weeks of detraining) are practically the same. Hwang et al., 2017. [PubMed]
In studies of untrained individuals, there appears to be some convergence on this two to three week timeline.9,10 Ochi et al. (2018) had 20 young, healthy, untrained participants undergo 11 weeks of resistance training, followed by six weeks of detraining.9 After three weeks of detraining, muscle thickness of the four muscles of the quadriceps, measured by ultrasound, had significantly decreased, compared to the values at immediately post-training. Relative to baseline, this amounted to a decrease from +12% at post-training to +9% after three weeks of detraining, on average.
Ogasawara et al. (2011) conducted a study where eight untrained participants underwent six weeks of training, followed by three weeks of detraining.10 Using MRI to measure muscle CSA, the triceps brachii and pectoralis major increased by an average of 9% and 14% respectively, after six weeks of training. Following detraining, muscle size relative to baseline had decreased to +7% in the triceps brachii and +8% in the pectoralis major, on average. Interestingly, from a statistical significance perspective, the triceps brachii was still significantly elevated above baseline, while the pectoralis major was not.
These studies tell us that you probably won’t see noticeable muscle loss within two weeks of detraining, as long as you’re bothering to get up and get dressed.
But this appears to be the cutoff. Sometime shortly after two or three weeks, most people will begin to notice some muscle shrinkage. This is the same timeframe muscle researchers Fisher and Steele cited in their review of evidence-based recommendations for hypertrophy, with quote “up to three weeks” being the maximum time frame you can take a break without fear of atrophy (or muscle loss).11
The three week time frame also makes an appearance in the Ogasawara (2013) data I’ve talked about on my YouTube channel several times before.12 Here, they had a group of seven participants alternate between six weeks of resistance training and three weeks of detraining for 24 weeks. MRI was used to measure muscle size of the triceps brachii and the pectoralis major. Looking at the figures, even though we do see dips in muscle mass after three weeks of detraining, it’s impossible to tell if that muscle loss happened gradually and evenly over those three weeks, or if there was a hard drop off after, say, two weeks. Furthermore, some experts claim that this isn’t actually true muscle loss, but rather mostly just a loss of glycogen and water stores inside the muscle. There could be something to this hypothesis, given that research shows that both total body water and glycogen can increase with resistance training.13,14 Unfortunately, because most of the literature in this area has focused on endurance training, there is little research exploring what happens to these muscle stores in the first several weeks of resistance detraining. There is some room for skepticism with the “glycogen hypothesis” because the same Hwang et al. (2017) study we mentioned earlier showed no change in total body water with two weeks of detraining. Perhaps this isn’t surprising, given that this study didn’t detect any change in muscle mass in the first place.8
In my opinion, I think there’s probably something to it. If it was merely water and glycogen being lost, it would help explain why rebounds seen after short breaks are so quick: we’d expect fuel stores to refill quickly once normal lifting resumes, restoring that “full” muscular appearance in a hurry.
Notice the dips in muscle cross-sectional area (CSA) during the weeks of detraining (weeks 6-9 and 15-18). Ogasawara et al., 2013. [ResearchGate]
Longer Training Breaks
Okay, so detraining for up to three weeks doesn’t seem to be too bad, as long as you’re moving around, but what about training breaks lasting longer than this? What if you’re forced to cancel your gym membership for, say, two months?
Luckily, a study from Léger and colleagues published in 2006 looked at this exact question.15 They put subjects on an eight week training program and then had them abruptly stop training for another eight weeks (about two months on, and then two months off). During the first two months, they saw a 10% increase in muscle size, but during the two months off, they saw those gains get cut in half. So, if we take a “glass half full” approach, even after two months of no lifting AT ALL, they still kept half the muscle they had built by just continuing everyday activities. I think that’s actually fairly encouraging, especially if you consider that many people should be able to do a little more than simply get out of bed and make it to the fridge.
It’s important to keep in mind, however, that these subjects were essentially noobies – they trained for two months and then took two months off – that’s it. People with more lifting experience might see less relative muscle loss in that same time frame – but it’s hard to say, based on the data available.
Looking back at the Ochi et al. (2018) study we touched on earlier, it took those participants eleven weeks to increase quadriceps size by 12%.9 After six weeks of detraining, quadriceps size had reduced to +7%. This presents a similar finding to the Léger and colleagues paper. In six weeks they had their gains cut from +12% down to +7%, on pace for losing roughly half of their gains in two months.
Beyond the two month time frame, it’s tough to speculate on how much muscle will be lost, as it will be highly dependent on three individual factors that we will turn our attention to below.
How Much Muscle Will I Lose?
So far, we’ve been speaking in very broad terms. How much muscle YOU actually lose will depend on THREE main factors: physical activity, caloric intake and protein intake.
1. Physical Activity: Physically, how little are you doing?
As we’ve seen, complete bed rest is in fact, quite a lot worse than just walking around and doing every day activities because those simple movements will, to some extent, mechanically activate most muscles. But, that itself is still quite a bit worse than doing high rep bodyweight workouts which is probably a bit worse than doing heavier training with weighted resistance.
Notice how the gap between bed rest and bodyweight training is much smaller than the gap between bodyweight training and progressive weight training. Scale is arbitrary and for illustration purposes only.
But, still, the gap between some form of resistance exercise and heavier training seems to be much smaller than the gap between just doing everyday activities and some form of resistance exercise. This is based on a 2011 study from Bickel and colleagues which found that even reducing training volume all the way down to 1/9th of what you were doing before, was enough to maintain muscle mass on average for 32 weeks – that’s over seven months.16 This is very encouraging. It tells us that even low volume “sub-optimal” workouts should be enough to keep most of your muscle hanging around for at least six or seven months.
To further establish this point, in a 16 week study of young untrained lifters, Tavares et al. (2017) showed that increases in quadriceps muscle size (measured using MRI) following eight weeks of resistance training could be maintained for another eight weeks, despite a ~54% reduction in training volume.17 Additionally, although in older adults (age, 70 ± 4 years), Trappe et al. (2002) showed that increases in muscle size of the thigh (measured using computed tomography) following 12 weeks of resistance training could be maintained for an additional six months, despite a 66% reduction in training volume.18
It’s worth noting that these papers were all conducted in untrained lifters. It’s possible that more experienced trainees wouldn’t be able to get away reducing their volume quite that much and still expect to keep all of their muscle. For example, one 2017 review by Schoenfeld & Grgic suggested that for well-trained lifters, a ~65% reduction in training volume (down to 5-7 sets per week per muscle group) should be enough to maintain muscle mass.9
Of course, because of individual differences in responses to different training volumes, it’s impossible to say exactly how much any given lifter will be able to reduce their volume and expect to maintain gains. Still, these studies give us some room for optimism that most of us can likely cut our volume at least in half and expect to roughly maintain our muscle mass for several months.
Some of you may be thinking “Great! So I can most likely maintain my gains with half of the volume I needed to build it, or less. Can I also get away with training lighter?”
Luckily, the answer to that second question is also “pretty much, yes.” It seems that muscle maintenance is a whole lot easier than muscle building. A 2017 meta-analysis by Schoenfeld et al. that found that low load training (<60% 1RM) was similarly effective to high load training (>60%) for building muscle.20 However, before you bust out the pink dumbbells, it’s worth noting that there does appear to be a low-end threshold for maximizing muscle growth somewhere around 20-30% 1RM.21 This means that once you start training so light that you need to do north of 50 reps just to get somewhat close to failure, you’re probably no longer optimizing your muscle growth.
Still, given the general theme that maintaining is easier than building, I would suspect that you can actually go quite light before you need to worry about “repping away” your gains, as long as you’re taking sets reasonably close to failure (not leaving more than three or more reps in the tank regularly). This is important to mention given that subjects all trained to failure in all of the aforementioned studies, highlighting the importance of trying to stay within three reps from failure for all sets, especially when training with light weights.
2. Caloric Intake: How little are you eating?
Unsurprisingly, how much muscle you lose depends on your daily total caloric intake. A new paper from Alan Aragon and Brad Schoenfeld notes that “a sustained energy deficit compromises muscular potential by inhibiting muscle protein synthesis and molecular anabolic signaling,” whereas “being in a caloric surplus provides the ideal milieu for promoting muscle growth.”22 The message is clear: you should eat at caloric maintenance or in a slight caloric surplus, if your main goal is to avoid muscle loss. This is especially true if you are training in a limited capacity or not training at all.
If you aren’t sure how to figure out your maintenance calorie intake, the easiest way is to simply multiply your bodyweight by 15 to 16, and then simply observe your weight trends over time. If you maintain your average weight over a few weeks, then you have likely found your maintenance intake. On the other hand, if you lose weight or gain weight on average, you will need to adjust your calories up or down to reach maintenance. I explain this in much more detail in my Ultimate Guide To Body Recomposition in the chapter on setting up the diet.
3. Protein Intake: Are you eating enough?
Thirdly, sufficient protein intake is crucial when it comes to preserving muscle mass. The same review from above cites 1.6 to 2.2 grams of protein per kilogram of bodyweight (so about 0.7 to 1 gram per lb) as a good range for drug-free, non-dieting trainees.22 However, you may want to err on the high end or even slightly higher if you aren’t actually training. For example, if you weigh 75 kg (165 lb) and decide to stop lifting for several months, you should aim to eat at least 165 grams of protein per day to help offset the suppression in muscle protein synthesis from detraining.
Another thing many people worry about is age. Based on the mountain of research exploring age-related muscle-loss, (or sarcopenia), it would seem reasonable to assume that muscle loss from detraining, increases as you get older.23-29 However, this isn’t actually all that clear, at least not in cases of complete bed rest. According to a 2016 review in the journal of Frailty and Aging, “it appears that periods of muscle disuse result in muscle losses of a similar magnitude compared to the young.”29 However, these authors still highlight the “importance of muscle mass maintenance for metabolic health in aging”.
It’s also worth noting that the Bickel paper we discussed earlier found that the 1/9th training volume protocol was only enough to maintain muscle mass in the younger group and not in the older group. This could imply that individuals 60 and older require more volume to keep their gains sticking around.16
Alright – another quick interruption to make sure everyone’s on the same page. Let’s recap quickly. The best way to minimize muscle loss during a period of detraining is to:
- Do more physical activity rather than less (anything that places some tension on the muscle is much better than nothing, and you don’t need a whole lot to see an effect)
- Eat at least at caloric maintenance
- Aim to eat roughly 2.2 g/kg (1 g/lb) of protein per day.
Muscle Memory Rules
BUT (and this is a big BUT) even if you ignore all of my advice so far and decide to do absolutely nothing for the next two months, or even two years, not all is lost.
Remember Matt from the beginning of the article? Well, it took him about seven years of training to build his peak physique. Then, because he was completely bed ridden and fed only through an IV, it only took two months for him to lose all that muscle.
However – here’s the good news – it definitely didn’t take another seven years to build that muscle back. In fact, with just two months of retraining, he was able to pack all of his lost muscle back on. What took him seven years to build from ground zero, he was able to build back in just two months.
This is, of course, an example of the power of muscle memory: the idea that it’s much easier to rebuild lost muscle than it is to build new muscle from scratch. Keep in mind, this is currently a controversial topic in the scientific literature. Most of you are probably familiar with the now-famous pioneering study from 2010 showed that muscle nuclei that were formed during training stuck around … forever.30 This finding led to the original muscle memory theory: the idea that as soon as you start training again, those nuclei can start pumping out new muscle proteins and you rebuild all your lost muscle, lickity-split.
This figure shows the hypothesized mechanism for muscle memory that was proposed within the 2010 study in rodents. Since then, this model has been called into question by new research in humans, suggesting that myonuclei may actually be lost with detraining. Bruusgaard et al., 2010. [ResearchGate]
However, a new study from Snijders and colleagues, conducted on humans instead of rodents this time, found something different: myonuclei still increased with training, but went back to baseline after just one year of detraining.31 Since then, even more research has been published, calling the original myonuclear retention hypothesis into question.32-35 Additional research has also led many experts to wonder if epigenetic changes play a greater mechanistic role in muscle memory than myonuclear retention.35,36 Regardless, while the actual mechanism of muscle memory is currently up for debate again, the existence of the muscle memory phenomenon itself is not. Whether owing to nuclei retention or epigenetic modifications, muscle memory is real, and it will help you build back any muscle you lost a lot faster than it took you to build it in the first place.
And that’s a wrap for my first blog post. If you’d like to see a (slightly more simplified) audio-visual representation of everything laid out in this article, check out my latest YouTube video here. Also, I’m going to be releasing a free “bridge” program for everyone subscribed to my newsletter in the coming few weeks, so you know exactly what to do when coming back from a training break. You can subscribe to my newsletter here! How do you end a blog? Enjoy the references! Peace!
