This Is How Long It Takes to Lose Muscle Gains During a Fitness Break

When you’re sidelined by an injury or taking a well-deserved vacation but want to stay devoted to your fitness gains, you might have a burning question: How long does it take to lose muscle?

We’re here to keep you from worrying too much about losing those hard-fought gains: All the strength you’ve built up won’t just suddenly disappear. Keep reading for everything you need to know about the muscle loss timeline and what you can do to preserve as much muscle mass as possible during some time away from your regular strength training routine.

How Long Does It Take to Lose Muscle?

The length of time it takes to lose muscle depends on a number of variables, including how much you’ve been training up to this point. And there really hasn’t been enough high-quality research on the topic to make a one-size-fits-all prediction about when you can expect to see muscle loss, according to a 2022 review in the journal Muscles. 

But for most people, it will generally take about four to 12 weeks to notice visible muscle shrinkage, according to Jennifer Hankenson, MD, a physiatrist and assistant professor of orthopaedics and rehabilitation at Yale Medicine, who is also board-certified in lifestyle medicine.

For average exercisers (as opposed to devoted athletes), that window might narrow a bit to about four to six weeks, adds Leanna Ross, PhD, an assistant professor at Duke University School of Medicine and a member of the Duke Molecular Physiology Institute, where she researches the effects of exercise on cardiometabolic health and cardiorespiratory fitness.

While these are rough estimates, our experts agree you’re likely to notice muscle atrophy anywhere in those first three months when you take a break from working out. That’s when “you can actually see physically that the muscles aren’t quite as strong as they used to look,” Dr. Hankenson says. You may also start to feel weaker during that time period if you were to return to training, she adds.

There can be changes that happen even sooner—think as early as one to two weeks without any strength training—but you’re unlikely to notice those in the mirror. “There’s a minor reduction in your muscle glycogen and water content that would be visible at a microscopic level,” Dr. Hankenson says. You’re more likely to lose some cardio fitness in those first two weeks if you’re really not exercising, but muscle endurance and mass should stay relatively steady for a bit longer, according to a small 2022 study on young male runners in the European Journal of Sport Science.

After about 12 weeks, most people will have lost enough muscle to be back to their pre-training levels of strength and muscle size, Dr. Hankenson says. “If you go back to working out at that point, it’s going to feel like you’re starting from the beginning.”

Factors That Affect Muscle Loss

That four-to-12-week muscle loss time range is admittedly wide. Because every body is different, your experience with losing muscle will be different from your friend’s or workout partner’s. How fast your muscles shrink depends on a number of factors, including:

How Long It Takes to Build Muscle Back

Just like the lifestyle factors above mean everyone loses muscle at different rates, everyone gains it back at different speeds too. There’s no precise timeline everyone will follow when it comes to rebuilding lost muscle. In general, though, it takes about four to 12 weeks to build visible muscle, the same rough timeline it takes to lose visible muscle.

But if you’re used to strength training, you have a leg up: There’s some muscle memory stored in your body and evidence that you might build your muscle back faster than if you were truly starting from scratch, Dr. Hankenson says. “There’s some protection in having maintained physical activity [until that point],” she says. “Because some of us do have unexpected illnesses, injuries, or life events that can take us away for even three months or so. But hope is not lost—you can get back into it.”

Some of Ross’s research shows certain measures of fitness and heart health might bounce back more quickly even years after a period of regular exercise. And other research indicates that there are cellular changes that occur after strength training that stick around even during long fitness breaks.

Best Practices to Remember When Building Muscle Back

You can support the muscle-rebuilding process by taking good care of the basics: Build back up to your regular exercise routine slowly but consistently so you don’t overdo it or up your risk of injuring yourself and stalling your progress. And remember to include plenty of rest days. 

“We want to tailor our programming to what our current capacity and ability is,” Ross says. “We don’t want to start where we ended up last time at the end of a program, especially after a long period of detraining, because we might not be at that same level. Make sure to start at an appropriate level and progress from there.”

Eat a nutritious diet with plenty of protein too. Aim for about 1 gram per pound of your body weight spread throughout the day from a range of high-quality protein sources so your body can optimize muscle protein synthesis.

And although it might not seem as obvious, make sure you’re also getting plenty of sleep and managing your stress levels, Dr. Hankenson says. Otherwise, sleep deprivation and sky-high stress can make it harder to stick to your workout or nutrition plans.

How to Prevent Major Muscle Loss During a Fitness Pause

There are going to be periods in your life when you exercise less than you’re used to. And there’s absolutely nothing wrong with taking some time off. In fact, some athletes swear by the occasional deload week.

But if you, for example, want to scale back while you visit family over the holidays or you need to take it easy during a tough life chapter, there are some simple steps you can consider taking to prevent major muscle loss in the meantime:

The Takeaway

How long it takes to lose muscle depends on a number of factors, including your age, your diet, your current fitness level, and how much activity you get during your time off from strength training. In general, it may take around four to 12 weeks for you to notice any visible muscle shrinkage, and it may take about the same timeline to build that muscle back.

Maintaining some level of physical activity during a period away from the gym (such as by walking more or taking the stairs) can help prevent major muscle loss during your break, as can getting plenty of rest, water, and protein. And don’t worry too much: If you’ve trained in the past, your cells and muscles have ways of “remembering” the effects of your previous workouts and will bounce back more quickly than you might expect.