How Long Does It Take to Lose Muscle Mass?
So: You can’t work out — on account of illness, work stress, gym closure, or life upheaval. It happens. As you get your life back on track, you may start to worry about your waning fitness. How long can you expect to keep the muscle mass you built in the weeks, months, or years you’ve been diligently working out?
The answer depends on a number of factors, but the good news is that the damage to your hard-won muscle mass may be less extensive — and more easily reparable — than you think. And that applies even if you have to take a lengthy break from strength training.
How Long Does It Take Men and Women to Lose Muscle Mass?
First the bad news: Atrophy — loss of muscle mass — is real. When you stop challenging your muscles, they lose both strength and size. That’s to be expected.
Like a high-end sports car, an athletic body requires more energy to maintain than one that’s less muscular, so when you no longer need it, your body offloads mass it doesn’t need. “The training principle of reversibility is real,” says exercise physiologist and fitness podcaster Dr. Lonnie Lowery, Ph.D., R.D. “Use it or lose it.”
In certain cases, muscle can atrophy alarmingly fast. Bedrest, for example can cause a 12 percent loss of muscle strength per week. And exposure to zero-gravity can result in a 20 percent loss of muscle mass after only five to 11 days.
But those are extreme cases. If you’re a disciplined, three- to five-day-a-week exerciser who has to reduce your activity to walks, housework, and the like for an extended period, studies have found you can probably get away with about a three-week break before you start to lose strength and muscle mass.
But strength and muscle loss doesn’t happen all at once. A 2015 study of middle-aged men and women who strength-trained for 16 weeks maintained some added strength and endurance even after a training break of a similar duration. So your muscle mass won’t melt away like candle wax if circumstances prevent you from exercising — even for an extended period.
Do Trained Athletes Lose Muscle Mass Slower?
Elite athletes lose some markers of fitness faster than the general population. The VO2 max of high-level runners, for example — a key measure of cardiovascular function — can drop up to 12 percent in two weeks.
But trained athletes can preserve much of their muscular strength, size, and endurance for periods longer than two weeks. The lesson? Once attained, muscle mass is relatively hard to get rid of. That’s likely for the same reason why it’s hard to gain in the first place: there’s just not a lot of change — up or down — in muscle mass on a week-to-week basis.
“It takes several weeks to notice [changes],” Lowery says. “Even in a lab that measures body composition.”
Does Age Play a Role in Muscle Loss?
In healthy adults, muscle mass peaks around age 30 and declines thereafter at a rate of 3-5 percent per decade. So when it comes to preserving or gaining lean mass, the over 30-crowd is swimming against a current of muscle loss. The younger crowd is not.
Still, that current is a slow one. For the average person weighing 150 to 200 pounds, a 1 percent loss of muscle mass is less than two pounds of muscle. And that’s what you’re likely to lose in a full year without any formal exercise.
How to Minimize Muscle Loss During a Break
Want to keep as much muscle as possible while you’re on an involuntary gym holiday? Try these tips.
You can maintain, and even gain, muscle mass very effectively without a gym or much equipment — you just need some creativity and commitment. (Here are just a few programs that can help you do that). And even a small amount of formal exercise — say, 30 minutes 2 to 3 times a week — can help you hold onto your muscle mass and strength.
“Some type of weight bearing, even with calisthenics or a single dumbbell or kettlebell, will help fight atrophy,” Lowery says. You don’t need a complex program or expensive equipment when all you’re trying to do is keep from backsliding — you just need to work hard and stay consistent.
2. Don’t panic
If you do lose some mass during your break from training, “muscle memory” will be your friend when you get back into the swing of things. Strength-trained women in a 2017 study regained much of the strength they lost in their seven-month break after just six weeks of training.
3. Keep up the protein
If you’re so crunched you simply can’t squeeze in any exercise, don’t cut protein drastically. In fact, Lowery recommends keeping protein intake high — close to a gram per pound of bodyweight. “Athletes tend to think about protein intake during times of gains,” says Lowery. “But it’s also important to prevent losses.”
4. Switch your focus
Most lifters give short shrift to cardiovascular fitness and mobility. But the research above suggests that they’re among the first things to go during a break from exercise. So one strategy during an enforced layoff is to switch your focus from muscle building to boosting your cardio fitness, flexibility, and mobility.
Equipment demands are minimal, and the new stimulus will likely do your entire body good. That way, when you get back to your lifting routine, you’ll have lost minimal strength and muscle. You’ll also be leaner, more mobile, and more enduring than ever. Not a bad tradeoff for a few weeks off from pumping iron.
5. Trust your training
Finally, if you’re a very dedicated exerciser and rarely take more than a day or two off from training, it’s possible that a break of up to three weeks might actually benefit you. Many gung-ho lifters spend their lives “overreaching” — pushing their bodies to the brink every workout — and have forgotten what full recovery feels like.
If that’s the case for you, embrace the time off as an opportunity to heal, grow, and recover more completely. You might be surprised by how good your body feels — and how well you perform — after some dedicated R’n’R.