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Here's How Fast You'll Lose Muscle If You Stop Exercising

A trainer reveals what happens to your muscles when you take a break from exercise.
FACT CHECKED BY Alexa Mellardo

Everyone needs a break from time to time—even your muscles. Sometimes, life throws you a curveball, like an unexpected illness or a busy schedule that keeps you away from the gym. Other times, you may find yourself hitting the beach for a few weeks or simply needing a breather from your regular workout routine. While taking a break can be a much-needed respite for your body and mind, worrying about losing the muscle mass you've worked so hard to build is natural. As a certified strength and conditioning specialist (CSCS), I'm here to break down how fast you lose muscle from taking an exercise break.

The thought of losing strength and definition can be concerning, especially if you've invested much time and effort into building your physique. So, I have you covered with everything you need to know about what happens to your muscles when you take a break from exercise and how to recognize the signs of muscle loss.

Rest assured that your body is resilient and can regain your muscle mass when you're ready to get back into the swing of things. I want you to leave this article knowing that missing a few workouts, or even a week or two, won't spell your gym routine downfall.

How fast can you lose muscle if you take a break from exercise?

muscle loss concept

Muscle loss, also known as muscle atrophy, can begin surprisingly quickly once you stop exercising. Significant muscle loss can typically start within two to three weeks of inactivity. The exact rate of muscle loss depends on several factors, including age, fitness level, diet, and overall health—lifestyle factors might be the most important aspect. Athletes and those with a higher baseline of muscle mass may initially experience a slower rate of muscle degradation than those who are less fit.

During the first couple of weeks, you might notice little difference. This period is often called the "honeymoon phase," where your muscles retain their size and strength despite the lack of exercise. However, after about two weeks, muscle protein synthesis—the process through which your body builds and repairs muscle tissue—begins to slow down.

By the three-to-four-week mark, noticeable muscle atrophy can set in, accompanied by a decline in strength and endurance. In an October 2022 study in Scientific Reports, the rate of atrophy was highest in the third and fourth weeks, with protective factors of muscle atrophy, including BMI and a lower initial thickness of lean muscle tissue.

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How to tell when you're losing muscle:

woman wondering why am I always tired, yawning at work

Recognizing muscle loss can be tricky because it doesn't happen overnight. Not everyone can access scientific measures such as a bod pod, DEXA, or skinfold measurements to track one's open body composition.

One of the first signs might be a decrease in strength. If once-easy activities, such as lifting weights or climbing stairs, become more challenging, this could indicate that you're losing muscle mass. Self-awareness is key in your fitness journey.

Additionally, you might notice changes in your body composition. Muscles might appear less defined, and you could see increased body fat as your metabolism adjusts to the lower activity level.

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Another clear sign of muscle loss is a noticeable drop in your energy levels. When you lose muscle, your body becomes less efficient at performing physical tasks, leading to quicker fatigue and decreased stamina. You might feel more tired after activities that previously didn't wear you out. Even everyday tasks like carrying groceries, playing with your kids, or taking a brisk walk can start to feel more exhausting. Monitoring these shifts in your energy and endurance can help you determine if you're experiencing muscle atrophy.

Pay attention to the loss of muscle definition. As your muscles atrophy, they may start to lose their firm, defined appearance. You might notice that areas of your body where muscle definition was once prominent, such as your arms, legs, or abdomen, begin to look softer and less sculpted. This change in appearance, combined with a decline in strength and energy, can be a clear indicator that muscle loss is occurring. This could even impact how your clothes fit, another clue that you might be experiencing muscle atrophy.

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How to regain muscle mass:

happy woman lifting weights, concept of how many days a week to exercise for results

Regaining lost muscle mass involves specific exercises like resistance training, proper nutrition, and adequate rest. Resistance training, such as weight lifting or bodyweight exercises like pushups and squats, is crucial because it stimulates muscle protein synthesis, helping to rebuild and strengthen muscles.

Aim to gradually reintroduce these exercises into your routine, starting with lighter weights and lower intensity before progressing to more challenging workouts. Gradual progression is necessary whether you're returning from a vacation hiatus, sickness, or a needed break from the gym.

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Nutrition plays a vital role in muscle recovery as well. Ensure you're consuming enough protein, as it provides the building blocks needed for muscle repair and growth. Protein-rich foods like lean meats, dairy, eggs, beans, and legumes should be staples in your diet.

Additionally, consider increasing your overall calorie intake slightly to support muscle growth. Staying hydrated and maintaining a balanced diet with sufficient calories will support your overall fitness goals.

Finally, don't underestimate the power of rest. Muscles grow and repair themselves during rest periods, so getting adequate sleep and allowing time for recovery between workouts is essential. With a well-rounded approach that includes exercise, nutrition, and rest, you can effectively regain lost muscle and return to your pre-break fitness level.

Jarrod Nobbe, MA, CSCS
Jarrod Nobbe is a USAW National Coach, Sports Performance Coach, Personal Trainer, and writer, and has been involved in health and fitness for the past 12 years. Read more about Jarrod
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