What Medical Conditions Can Cause Muscle Wasting?

Muscle wasting (atrophy) is the loss of muscle mass and strength, often caused by advancing age or physical inactivity.

Wasting of muscle tissue can also occur with malnutrition and various nerve or muscle-related health conditions such as amyotrophic lateral sclerosis (ALS), muscular dystrophy, or spinal muscular atrophy.

Chronic diseases associated with immobility or a sedentary lifestyle due to pain or disability like arthritis or multiple sclerosis are additional causes of muscle atrophy.

This article will explore several causes of muscle wasting and how some cases can be reversed with physical and nutritional therapies. Strategies to possibly prevent or slow muscle wasting will also be reviewed.

Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS)—formerly known as Lou Gehrig’s disease—is a neurological condition that causes skeletal muscle wasting due to the death of motor neurons.

Skeletal muscles are connected to your bones, allowing you to move and function. They comprise 40% to 50% of a person’s body’s mass.

Motor neurons are nerve cells that carry messages from your brain and spinal cord about movement to your muscles.

ALS is most likely to manifest between ages 55 and 75 and is characterized by a steady worsening of symptoms over time.

The hallmark symptom of ALS is muscle weakness, which progresses in a relatively predictable pattern to muscle wasting, twitching (fasciculations), and being unable to move, chew, talk, or breathe (paralysis).

The cause of ALS remains unknown, and the disease is eventually fatal, usually within a matter of years after detection.

Other potential ALS symptoms are:

• Muscle stiffness and cramps
• Stumbling, falling, and dropping things
• Slurred speech or trouble forming words (dysarthria)
• Difficulty swallowing (dysphagia)
• Breathing problems
• Drooling
• Constipation

Muscular Dystrophy

Muscular dystrophy is a group of inherited diseases (more than 30) that causes skeletal muscle weakness and wasting that worsens over time.

The genes involved in muscular dystrophy normally code for muscles that are healthy in structure and function. Muscle degeneration occurs when one of those genes is mutated (a change in DNA sequence).

Degeneration means the thousands of fibers comprising certain muscles are damaged, thinned out, and eventually die.

Depending on the type of muscular dystrophy, factors like age of onset (e.g., childhood vs. adulthood), symptom severity, which muscles are affected, and life expectancy vary.

Also, while skeletal muscles are the primary organ affected, other tissues and organs, such as the heart, lungs, or digestive tract, are affected in some types.

Examples of common types of muscular dystrophies include:

• Becker muscular dystrophy develops almost always in males (people with chromosomes XY instead of XX) because the disease is X-linked recessive. The mutated gene is on an X chromosome, and the condition doesn’t manifest if the person has a second X chromosome with a healthy copy of the gene. Muscle weakness develops in childhood or teenage years.
• Duchenne muscular dystrophy, like Becker muscular dystrophy, primarily affects male children as it’s inherited in an X-linked recessive pattern. Symptoms tend to be more severe, and there is an earlier onset, usually around 2 to 3 years of age.
• Facioscapulohumeral dystrophy is associated with facial and shoulder muscle weakness and is usually inherited in an autosomal dominant pattern (one copy of the mutated gene causes the disease, and the gene is not on the X or Y chromosomes). It can affect people of any sex. Symptoms usually develop before age 20.

Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is a group of inherited diseases in which motor nerve cells are damaged and die, causing muscle weakness and wasting that worsens over time.

The incurable condition is inherited in an autosomal recessive pattern, meaning a mutated gene from each parent is necessary for the person to develop the disease.

There are five types of SMA (types 0 through 4), all varying in age of onset and severity. All forms, though, are characterized by widespread, symmetric muscle weakness that affects the muscles close to the body’s core (e.g., thighs, hips, upper arms, shoulders, and trunk).

Symptoms of SMA type 1 through 3 begin in infancy and childhood, whereas SMA type 4 is the mildest form and manifests during adulthood, usually between the ages of 30 and 60.

SMA type 0 is the most severe form and affects the fetus before birth. Once the baby is born, they experience severe muscle weakness and lack of muscle tone (hypotonia).

Since the muscles that control breathing are so weak, affected babies often die from respiratory failure, often within the first month.

Multiple Sclerosis

Multiple sclerosis (MS) is a neurological disorder that does not directly cause muscle atrophy like ALS or muscular dystrophy. However, muscle atrophy can occur secondarily as a result of the symptoms of the disease.

MS develops when a person’s immune system malfunctions and unpredictably attacks the fatty coating (myelin) surrounding nerve fibers in the brain and spinal cord.

Myelin is essential for transmitting signals between the brain and spinal cord and the rest of the body.

When myelin is damaged or lost in a process known as demyelination, various symptoms like fatigue, blurry vision, abnormal sensations, and bladder dysfunction can develop.

Muscle-related symptoms from demyelination in MS include:

• Weakness, especially in the arms and legs
• Shaking (tremor)
• Tightness (spasticity),
• Ataxia (loss of coordination)

The above symptoms may lead to further complications, such as falls, contractures (frozen joints), and foot drop, which causes a person to drag their foot or toes when walking.

They can also cause a person to lose or limit their ability to walk or function independently. When a person stops using specific muscles—for example, due to spasticity-related pain or fatigue—muscle wasting can develop.

MS can occur at any age but is typically detected between 20 and 40, and most people live near the same lifespan as the general population.

Aging

Age-related muscle loss occurs naturally as people age. This phenomenon—known as sarcopenia—manifests even in healthy, physically active individuals, beginning around the age of 40.

Sarcopenia is a gradual process that varies significantly from person to person. On average, after age 70, individuals experience a loss of about 1% of muscle mass and 3% of muscle strength, emphasizing the need for strategies to slow this decline.

Inactivity for Extended Periods

Research suggests that muscle atrophy occurs after three or four days of immobilization, which may develop after an acute illness, hospitalization, or recovery from surgery or injury. Even sitting at a desk day after day for hours on end can lead to muscle wasting.

Besides acute causes of inactivity, certain health conditions can cause temporary or permanent immobility—for example, multiple sclerosis (discussed above).

While not an exhaustive list, examples of other conditions that can make staying active difficult, if not impossible, include:

Malnutrition

Malnutrition is a state of imbalance between food intake and energy requirements and is another prominent cause of muscle wasting.

According to the Global Leadership Initiative on Malnutrition (GLIM), at least one observable (phenotypic) criterion and one cause-related (etiologic) criterion is required for the diagnosis of malnutrition.

Malnutrition is frequently seen in older adults but is also common in individuals with certain health conditions and scenarios like:

Besides causing muscle wasting and diminished strength, malnutrition is associated with physical disability, depression, loneliness, and an increased risk of falls and bone breaks (fractures).

Other Possible Causes

Several other health-related conditions/scenarios, as well as certain medications, can cause muscle wasting.

For example, severe burn injuries and sepsis trigger a whole-body stress and inflammatory response that leads to muscle wasting.

High-dose administration of glucocorticoids (steroids), such as prednisone, causes skeletal muscle wasting by reducing muscle fiber amount or density.

While not a complete list, other causes of muscle atrophy include:

• Cachexia, also known as wasting syndrome, is a complex metabolic condition associated with extreme muscle and fat loss despite a person eating adequate or high-calorie meals. It’s related to various chronic illnesses, such as cancer, chronic kidney disease, heart failure, and human immunodeficiency virus (HIV).
• Diabetic peripheral neuropathy occurs when peripheral nerves (located outside the brain and spinal cord) are damaged from high glucose (sugar) levels, causing muscle wasting, especially in the feet and lower legs.
• Cushing syndrome is the overproduction of the stress hormone cortisol by the adrenal glands (small glands that sit upon your two kidneys). Excess cortisol causes muscle wasting, especially in the hips and thighs, making it difficult to climb stairs.
• Guillain-Barré syndrome (GBS) occurs when the immune system attacks the peripheral nerves. Muscle wasting occurs from loss of nerve supply to muscles and immobilization from the effects of the disease.

How Muscle Wasting Is Treated

Maintaining sufficient skeletal muscle mass is crucial for a long and healthy life. Skeletal muscle wasting impairs functioning, reduces quality of life, and makes a person more vulnerable to hospitalization and death.

Currently, the treatment of muscle wasting remains complex, as the cause varies greatly from person to person and may be multifactorial.

Nevertheless, muscle strength can be improved or regained in many cases with the right interventions—typically physical therapy, exercise, and eating nutritiously.

Physical Therapy and Exercise

Physical therapy or exercise is the best treatment for muscle wasting. A physical therapist can teach a person safe and appropriate exercises to recover from or slow muscle wasting.

Depending on the underlying cause of your muscle wasting, physical therapy can also help in the following ways:

• Improve balance and flexibility
• Ease pain
• Prevent falls
• Delay the need for adaptive devices

Keep in mind that physical therapy regimens are tailored to an individual’s needs and goals. As an example, low-impact exercise such as swimming may be preferred for individuals with disuse-related muscle wasting due to pain from arthritis or spasticity.

If a person is bedridden, passive or active range-of-motion exercises can be performed to help keep joints and muscles flexible and functional for as long as possible.

In people with chronic illnesses like diabetes who cannot exercise regularly, acupuncture plus low-frequency electrical stimulation can help prevent muscle loss. This therapy involves inserting thin needles into specific muscles. The needles are connected to electrodes that deliver low-frequency electrical impulses, thereby mimicking exercise.

Nutritional Therapy

Research suggests that the Mediterranean diet can protect against muscle wasting in older adults. The Mediterranean diet emphasizes a high intake of whole grains, olive oil, beans, lentils, nuts, fish, fruits, and vegetables.

Protein intake also appears vital in preventing muscle loss in older adults and perhaps other cases of muscle atrophy, as protein makes up the bulk of muscle tissue.

Typical protein sources include meats, poultry, fish, legumes, tofu, eggs, nuts, milk, cheese, and yogurt. That said, further investigation is needed to determine the ideal source and amount of dietary protein.

Other vitamins, minerals, and nutrients that may improve muscle mass or protect against muscle loss include:

As with protein, more research is needed to understand their impact and, if beneficial and safe, dosage and frequency. Always speak with a healthcare provider before trying any new supplement.

Ways to Prevent Muscle Wasting

Muscle wasting is inevitable in certain incurable diseases, like ALS. However, it’s avoidable or can be slowed in other cases, such as physical inactivity or increased age.

For instance, if you live a sedentary lifestyle, now is the time to get active. Start exercising under the guidance of a healthcare provider or physical therapist.

An exercise regimen should include both aerobic and strength training exercises. Typical aerobic exercises are walking, jogging, cycling, cross-country skiing, and swimming. Strength training exercises often use free weights, weight machines, medicine balls, or resistance bands.

Likewise, if you have an upcoming surgery requiring a long recovery, talk with your healthcare provider about ways to help preserve muscle mass as you recuperate.

Besides exercise, eating a nutritious diet that includes protein is crucial. Aim for around 0.35 grams per pound of body weight per day.

Also, it’s sensible to see a registered dietitian nutritionist (RDN) who can help you devise a well-balanced diet that fits your needs and goals.

Summary

Muscle wasting (atrophy) is the thinning of muscle tissue, a natural consequence of aging called sarcopenia. Sarcopenia can be accelerated by malnutrition or immobilization due to a sedentary lifestyle, hospitalization, or disease (e.g., arthritis or stroke).

Various health conditions like amyotrophic lateral sclerosis (ALS), muscular dystrophy, spinal cord atrophy, cachexia from cancer, severe burns, or nerve damage from diabetes can also cause muscle wasting.

While not all cases of muscle wasting can be reversed or improved, some can, especially those related to physical inactivity. In fact, exercise is the most essential treatment for muscle wasting, along with eating a nutritious and protein-rich diet.

If you are experiencing symptoms of muscle wasting, see a healthcare provider. They will perform a medical history, physical exam, and diagnostic tests.

Depending on the results, you may be referred to a physical therapist, nutritionist, or neurologist (a physician specializing in the brain and nervous system).