How Long Does It Take to Lose Muscle Mass?

Discover how quickly muscle mass can be lost during a break from physical activity and explore effective strategies for rebuilding it quickly.

A woman's muscled back
Sarah Zimmer, PT, DPT
— Signos
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Updated by

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Science-based and reviewed

July 19, 2024
June 21, 2024
— Updated:

Table of Contents

Losing muscle mass, a phenomenon known as muscle atrophy or, more severely, sarcopenia, can occur for various reasons, including a lack of physical activity, poor nutrition, aging, and certain medical conditions, including insulin resistance.1, 2 This process doesn't happen overnight, as typically, it involves a gradual decline influenced by several factors that vary significantly from person to person. Understanding these variables is crucial for anyone looking to maintain or regain their muscular strength, fitness level, and overall health.

In this article, we will explore the most common contributing factors of muscle loss, delving into how quickly one can expect changes in muscle mass under different circumstances. We will discuss the physiological mechanisms behind muscle atrophy, the role of diet and exercise in mitigating muscle loss, and practical strategies to preserve muscle mass during periods of inactivity. By the end, you will have a comprehensive understanding of the rate and determinants of muscle loss and effective strategies to combat this process, ensuring better muscle health and a stronger body even as you age.


Understanding the Rate of Muscle Loss

Muscle mass plays a vital role in overall physical function, metabolic health, and quality of life. Muscle loss can lead to decreased strength, reduced mobility, and a higher risk of falls and injuries, particularly in older adults. Moreover, muscle tissue is metabolically active, meaning it helps regulate blood sugar levels and maintain a healthy weight. As muscle mass decreases, so does metabolic rate, which can contribute to weight gain and associated health issues like type 2 diabetes and cardiovascular diseases.3 

The rate of muscle loss can vary widely between athletes and non-athletes due to differences in activity levels, age, fitness, and overall health. Muscle atrophy can begin within a few weeks of reduced physical activity for non-athletes or individuals who are generally inactive. Studies suggest noticeable muscle loss and a decline in muscle protein synthesis can occur in as little as two to three weeks of inactivity.4 

The rate can be more pronounced in older adults, who naturally lose muscle mass more quickly due to age-related factors and increased adipose buildup within muscle tissue.5 Without regular exercise, particularly resistance training, non-athletes, and older adults may experience a gradual but steady decline in muscle strength and size.

Athletes, on the other hand, may experience muscle loss at a different rate due to their higher baseline levels of muscle mass and conditioning. While the onset of muscle atrophy can also begin within two weeks of inactivity, athletes often maintain muscle mass longer due to their previous training and muscle memory. 

However, the rate of muscle loss can still be significant if the period of inactivity is extended, with muscle strength and size diminishing noticeably within a month. The extent of muscle loss can be mitigated by maintaining some level of physical activity as well as adequate nutritional intake.6 

Elements That Impact Muscle Loss

A man lifting weight

To effectively combat muscle atrophy, it is essential to understand the many contributing factors, such as diet, genetics, and fitness levels, not to mention the incidence of injury and aging, which equally affect the rate and extent of muscle loss. By identifying and addressing these contributing factors, you can develop comprehensive strategies to maintain muscle mass and optimal physical well-being.

  • Level of Fitness: Individuals with higher baseline levels of fitness and muscle mass tend to lose muscle more slowly than those who are less fit. Regular exercise and weight training help maintain muscle mass and strength.
  • Genetic Factors: Some people are naturally predisposed to retain muscle mass more effectively due to their genetic makeup. This is one that is out of your control, but it is important to note when tracking your progress. 
  • Dietary and Nutritional Habits: Adequate carbohydrate and protein intake is crucial for muscle maintenance. Poor nutrition or inadequate protein consumption can accelerate muscle loss. Additionally, deficiencies in essential nutrients like vitamins and minerals can negatively impact muscle health.7
  • Workout Regimen: The type, intensity, and duration of exercise directly affect muscle preservation. Resistance training, in particular, is essential for maintaining and building muscle mass.
  • Frequency of Training: Regular and consistent exercise is key to preventing muscle atrophy. Exercising only one day per week may be insufficient to maintain muscle mass over time.
  • Sleep Patterns: Quality sleep is essential for muscle recovery and growth. Poor sleep, especially over multiple days, can hinder muscle repair and lead to increased muscle loss over time.8
  • Aging: Muscle mass naturally declines with age, a condition is known as sarcopenia. Older adults need to be particularly proactive in engaging in resistance training and proper nutrition to combat age-related muscle loss.
  • Physical Injuries: Injuries that limit mobility or lead to prolonged periods of inactivity can result in rapid muscle atrophy. Rehabilitation and physical therapy are critical to restoring lost muscle mass and mitigating the total atrophy that occurs in the time away from activity. 

<p class="pro-tip"><strong>Also Read: </strong><a href=how-long-does-it-take-for-muscles-to-recover>How Long Does It Take Muscles to Recover?</a>.</p>

How Do I Know if I’m Losing Muscle?

Recognizing muscle loss can be subtle initially. Key indicators include a decrease in strength in everyday tasks (e.g., going upstairs) and in the gym. Over time, you may start to notice a reduction in muscle size, particularly in areas like the arms, legs, and shoulders. Unexpected weight loss without changes in diet or physical activity might also suggest muscle loss, as muscles are denser than fat, and their reduction can decrease overall body weight faster.

Measuring muscle loss can be done through various methods. Regularly tracking your strength using specific exercises and recording the weights and repetitions can provide insights into any decline in muscle function. Body composition analysis, such as bioelectrical impedance analysis (BIA) or dual-energy X-ray absorptiometry (DEXA), can accurately measure muscle mass and body fat. Additionally, circumference measurements of key muscle groups, like the biceps, thighs, and calves, can track changes in muscle girth. Combining these methods provides a comprehensive view of muscle health, helping to detect and address muscle loss effectively.

4 Tips for Reducing Muscle Loss During a Break

When taking a break from regular physical activity, adopting strategies that help minimize muscle loss and maintain overall health is essential. Check out these tips and effective methods to combat muscle atrophy during periods of reduced exercise. By implementing one or all of these tricks, you can protect your hard-earned muscle gains and continue to support your fitness goals.

  • Maintain Protein Intake: Ensure you continue to consume adequate amounts of protein to support muscle maintenance and repair, even when you are not training intensely.
  • Shift Your Focus: Use the break as an opportunity to focus on other aspects of fitness, such as flexibility, balance, and cardio, which can support overall muscle maintenance.
  • Stay Calm: Stress can negatively impact muscle health. Practice stress-relief techniques such as meditation, using the sauna, deep breathing, or gentle yoga to keep stress levels in check.
  • Rely on Your Training: Trust that your previous training has built a solid foundation. Muscle memory can help you regain strength more quickly once you resume regular exercise.

6 Strategies for Rebuilding Muscle Mass

A woman doing a plank workout

So you’ve lost some muscle mass and are begging to get it back. This section offers a comprehensive list of approaches to restore lost muscle tissue and enhance overall muscular health. By understanding and implementing these methods, you can embark on a structured path toward muscle building, overcoming setbacks, and achieving your fitness goals with confidence and resilience.

  • Sustain Calorie Intake: Consume more calories than you burn to provide your body with the energy it needs to build muscle. Focus on nutrient-dense foods to support overall health.
  • Consume Protein: Include high-quality protein sources in your diet, such as lean meats, fish, eggs, dairy, legumes, and plant-based proteins, to supply the necessary amino acids for muscle repair and growth.
  • Strengthen Muscles With Training: To stimulate muscle growth, engage in regular strength training exercises, including weightlifting, resistance band exercises, and bodyweight workouts.
  • Progressive Overload: Gradually increase the weight, resistance, or intensity of your exercises to challenge your muscles and promote growth continually.
  • Rest and Recovery: Incorporate rest days and ensure you get enough sleep to allow adequate time for muscle recovery between workouts. Muscles grow and repair during periods of rest.
  • Consistency: To see sustained muscle growth over time, maintain a consistent workout and nutrition regimen. Sporadic efforts are less effective than a steady, ongoing commitment.

Learn How to Improve Your Nutrition and Monitor Your Glycemic Index Levels With Signos’ Expert Advice

If you have more questions on improving your health, fitness, and nutrition, seek the expert advice of the Signos continuous glucose monitor and Signos team. A continuous glucose monitor (CGM) can give you the insights to make smarter nutrition and exercise choices. The Signos app provides a unique, personalized program to help you lose weight and reach your health goals. Take this quiz to see if Signos is a good fit for you and reach your goals faster than ever before.

<p class="pro-tip"><strong>Learn More: </strong><a href=how-long-does-it-take-to-get-fit-again>How Long Does It Take To Get Fit Again? Here’s What to Know</a>.</p>

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Topics discussed in this article:


  1. Rosenberg IH. Sarcopenia: origins and clinical relevance. Clin Geriatr Med. 2011 Aug;27(3):337-9. doi: 10.1016/j.cger.2011.03.003. Epub 2011 Jun 8. PMID: 21824550.
  2. Guillet, C., & Boirie, Y. (2005). Insulin resistance: a contributing factor to age-related muscle mass loss?. Diabetes & metabolism, 31, 5S20-5S26.
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About the author

Sarah is a Doctor of Physical Therapy, graduating from the University of Wisconsin Madison in 2017.

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