Unlike stubborn belly fat that never seems to go away, it is commonly thought that with muscle mass, if you don’t use it, you lose it. While this is partly true, it's a little more complicated than that.
Whether you're coming off an injury or a long break from the gym, you’re probably wondering how much damage your rest period has done to your gains. Or maybe you’re actually looking to slim down your muscle mass. Regardless, here’s everything we know about maintaining lean tissue based on science.
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Can You Lose Muscle?
You can ultimately lose any type of body weight including fluid, fatty tissue, and muscle - especially when cutting calories. However, your body tends to prefer burning fat over muscle when it needs the fuel.
Lean tissue is a precious mass that our bodies use to store nutrients, provide strength to our frame, and power our metabolism. For these reasons, your body tends to want to hang on to it as much as possible.
How to Lose Muscle
Unlike fat that requires a calorie deficit to lose, muscle loss can be achieved with inactivity alone through muscle atrophy. Muscle atrophy can also occur naturally as you age, and as a result of malnutrition - primarily low protein intake (1,2).
Muscle atrophy is the physical wasting or loss of muscle tissue resulting in decreased size and muscular strength.
How Fast Can You Lose Muscle?
How quickly muscle atrophy takes place depends on your current fitness level and the amount of time you were inactive.
The more muscle mass you have, the harder it is to maintain with inactivity and the more you'll potentially lose. In other words, fit individuals are likely to lose muscle mass more quickly than unfit individuals.
Some research suggests that you can start to lose muscle in as quickly as one week of inactivity - as much as 2 pounds if you are fully immobilized (3). And another study suggests your muscle size can decrease by about 11% after ten days without exercise, even when you aren’t bed ridden (4).
But before you panic and start regretting every vacation or week off you’ve taken, it is important to understand that true muscle atrophy typically takes place during times of injury or when you completely stop using your muscles for an extended period of time.
Having your leg immobilized for two weeks or more is different from taking a couple weeks off from weight lifting.
Additionally, a decrease in muscle size doesn’t always mean muscle loss, oftentimes it's from decreased fluids. When you take a break from training, water loss and glycogen depletion can cause your muscles to decrease in size by up to 20% in a week (5,6).
The after workout “pump” you’ve learned to love so much is directly tied to this and your glycogen and water store can return fairly quickly once you resume exercising (7).
Does Muscle Turn Into Fat?
Muscle and fat are two entirely different cell types and often require different nutrition and methods to increase or decrease.
The longer you take time off, the more your body composition begins to change. Muscle cells will shrink and your fat cells can expand, making you feel fluffier and less toned. But this does not mean your muscle is turning into fat - especially if you are eating the right amount.
However, if you are eating more calories than you need, this will result in fat gain alongside your muscle loss.
How to Tell if You Are Losing Muscle
If you are still able to move around, true muscle loss can occur after about 3 weeks of skipping your workouts.
The easiest way to tell if you are losing muscle is through body composition testing. Outside of this, pay attention to your strength, physical measurements, and body weight to help indicate any muscle loss.
How Long Does it Take to Regain Muscle?
If you stop training and muscle atrophy occurs, it is entirely possible to regain what you’ve lost. And thanks to muscle memory, it can happen faster than it took to gain that muscle the first time around.
As for how fast, some research suggests that it'll take you three times the amount of time you were inactive to regain the muscle mass that you've lost if you were fully immobilized (8). But this time-frame can depend on the person and whether or not you’ve been using your muscle at all.
Three Ways to Maintain or Regain Muscle Mass without Weights
If you can’t hit the gym and are worried about losing muscle mass or looking to regain the muscle mass you’ve already lost, here are three sure fire ways to help protect your lean tissue.
1. Maintain Your Calorie Intake
Weight loss of any kind occurs from decreased calorie intake (9). And on the flip side, eating too much while inactive can lead to excess fat gain. So one of the most crucial approaches to keeping your gains and maintaining your body composition is getting the right amount of calories each day.
As you decrease your calorie burn and overall output, readjust your daily intake accordingly using this TDEE calculator.
2. Use Your Muscles
Heavy lifting can support muscle strength but isn’t required to build muscle. All you really need to do is use them on a consistent basis.
Including any type of strength training or resistance training (bodyweight movements, exercise bands, etc.), even if only a few times a week, can help protect your lean mass (10).
Get access to daily workouts for home or the gym with the Trifecta App.
3. Eat Plenty of Protein
Muscles are made up of protein, and if your body isn’t getting enough protein through diet, your muscles are some of the first places you body will steal protein from to support your nutrition needs. So, making sure you're eating a high protein diet is crucial.
In fact, research even suggests that higher protein intake can help maintain your muscle in a calorie deficit, while you lose body fat instead (11). In some cases, you can actually build muscle and lose fat at the same time.
Learn how much protein you need and the best places to get it.
Get back on track with your workouts using this free 12-week workout plan for muscle gain, Fully scalable to your fitness level and weekly schedule and complete with weekly tracking and monthly fitness assessments so you can track your progress.