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What Happens To Your Body When You Stop Lifting Weights

Your muscles are designed to be worked. Here's what happens when you stop using them.
FACT CHECKED BY Alex Daniel

Anyone who's ever been cornered by a CrossFit enthusiast at a bar has likely heard all about the benefits of weight lifting. But the significant advantages of weight and strength training aren't something to scoff at.

Weight lifting makes the body do what it was meant to do: work, says Michael R. Deschenes, PhD, FACSM, a professor of kinesiology and health sciences and the chair of Kinesiology and Health Sciences at The College of William & Mary, and a fellow with the American College of Sports Medicine. "Weight training strengthens not only your muscles but also your skeletal system," Deschenes says. The stress it puts on your muscles creates microtears, which then heal and help your muscles grow larger and stronger, he explains.

Regular strength training is important to keep your muscles engaged and active, especially for people who otherwise lead relatively sedentary lifestyles (like most modern Americans). But sometimes, life asks us to put down the weights and take a break, whether it's due to injury, surgery, or just going on vacation. In which case…what happens to your body when you stop lifting weights for an extended period of time? Do all of your hard-won gains disappear? We asked the pros to break it down for us. And for some easy ways to start working your muscles more every day, don't miss The Secret Trick for Getting Fit Using Your Toothbrush.

1

You start to lose strength and muscle mass

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The first thing to change, Deschenes says, is your strength. "Strength goes down almost immediately," he says—within a single week. This is true for both men and women, but research he's worked on has found that women lose up to 29 percent of their strength, compared to up to 16 percent for men.

After three weeks without weight training, Deschenes says you start to lose muscle mass. This is because it takes longer for the body to build up muscle proteins, and therefore it takes longer for it to start losing those muscles. And for more some great workouts to try, learn why These 5-Minute Exercises Will Make You Sleep Like a Teenager.

2

You may lose bone density

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Going for a few weeks without strength training also affects your bone density, says Deschenes. This is because your bones (like your muscles) bulk up in response to weight in order to be better able to carry loads. But without the regular stimulus of weight or strength training, your bones will become less dense, too. This is a huge issue as you get older, because after the age of 30, people naturally start to lose bone mass. If gone unaddressed, low bone density can put you at an increased risk of osteoporosis and fractures.

3

Your metabolism may change

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A change in muscle mass (say, from stopping lifting weights) may also affect your metabolism—aka the chemical processes in your body that convert food into energy to keep you alive. "Muscles are some of the most active tissues in the body," says Deschenes. Weight lifting and other activities that build muscle mass can increase your metabolic rate, because your cells require lots of energy (in the form of oxygen and food) to perform. But when you lose muscle mass, Deschenes says, you're inherently not using up as much oxygen or calories, which slows down your metabolism.

Changes in metabolism aren't inherently good or bad. However, if your metabolism slows down due to reduced activity but you're still eating the same amount that you did when you were lifting weights, you may gain weight in the form of fat, adds Ahmed Helmy, MD.

4

You may increase your risk of diabetes

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Your body needs glucose (aka sugar) to function, and muscles play a surprising role in the process. "Muscle mass is the greatest depot of stored glucose [in the body]," says Deschenes. The liver has some, he says, but it's a much smaller amount. If you lose significant amounts of muscle mass, your body becomes more reliant on what is stored in the liver—which he says can lead to problems with blood glucose control and in more extreme cases, type 2 diabetes. Thankfully, building muscle mass (which you can do with, you guessed it, weight training!) is associated with a reduced risk of diabetes.

5

Good news: Most of these issues are reversible

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You might think all this means that you have to constantly lift weights or risk tons of negative side effects. But Deschenes emphasizes that not only does it take a long time to experience these changes, but you can also regain most of the ground you've lost by resuming weight training. That's because our bodies have a muscle "memory" that makes it easier to build back up existing muscle, he says. (The exact mechanism of how it works isn't entirely clear, but current research suggests that unused, atrophied muscle cells shrink rather than die off completely.)

"Don't be afraid to put down those weights for a week," he says, whether it's due to a vacation, a bad mental health spell, or recovery from surgery. "You could take two or three weeks off and be fine." Additionally, once you hit the muscle mass you're looking for, you don't need to lift every day to maintain it. "You can maintain your strength and muscle mass as little as one session a week," he says. So if you have to put down your dumbbells for a spell, don't worry: Your muscles will be ready to pick back up where you left off. And for more life-changing exercise advice, see here for the Secret Exercise Tricks for Keeping Your Weight Down for Good.

Jessie Van Amburg
Jessie Van Amburg is a freelance writer and editor who has covered health, nutrition, and lifestyle topics for top media outlets including Women's Health Magazine, TIME.com, and Well+Good. Read more