Muscle Loss in Legs and Buttocks: Causes and Treatment

Muscle loss in the legs and buttocks is a common but often overlooked concern that can affect people of all ages, from those recovering after injury or illness to older adults experiencing age-related sarcopenia. The causes range from simple inactivity to serious neurological or systemic conditions, and the appropriate response depends entirely on identifying what is driving the loss. This article explains the main causes, how doctors assess lower-limb muscle wasting, which conditions are most commonly linked to it, what treatments and exercises can help, and when to seek medical advice.

What causes muscle loss in the legs and buttocks?

Muscle loss in the legs and buttocks most commonly results from physical inactivity, ageing, nerve damage, systemic illness, or medicines such as corticosteroids, all of which disrupt the balance between muscle protein synthesis and breakdown.

Muscle loss in the legs and buttocks most commonly results from physical inactivity, ageing, or an underlying medical condition that disrupts the normal balance between muscle protein synthesis and breakdown. The medical term for significant muscle loss is sarcopenia when it is age-related, or muscle atrophy when it follows disuse, nerve damage, or systemic illness. A third pattern, cachexia, occurs in serious systemic disease such as cancer or advanced heart failure and involves active inflammatory-driven catabolism rather than simple disuse or ageing.

The lower limbs and gluteal muscles rely heavily on regular weight-bearing activity to maintain their mass. Prolonged bed rest, sedentary work, or immobilisation after injury can trigger atrophy relatively quickly. It is worth noting that some research suggests lower-limb muscle mass may be particularly sensitive to inactivity, though the degree varies between individuals.

Several biological mechanisms drive this process:

• Reduced anabolic signalling: Lower levels of testosterone, oestrogen, and growth hormone, which naturally decline with age, reduce the stimulus for muscle protein synthesis. This does not mean hormone replacement is appropriate for sarcopenia; it is not recommended unless a specific hormonal deficiency has been diagnosed and confirmed by a clinician.

• Neurogenic atrophy: Damage to the motor nerves supplying the quadriceps, hamstrings, or gluteal muscles, as seen in lumbar disc disease or peripheral neuropathy, causes the affected muscle fibres to waste.

• Systemic inflammation: Chronic conditions such as cancer, heart failure, and chronic kidney disease release inflammatory cytokines that accelerate muscle protein breakdown.

• Nutritional deficiency: Inadequate dietary protein or calorie intake, particularly in older adults, limits the raw material needed for muscle repair.

• Medicines: Certain medicines, including long-term systemic corticosteroids and statins, can cause or worsen proximal muscle weakness.^[7][8] Alcohol misuse is also a recognised cause. If you have developed new muscle weakness after starting a medicine, discuss this with your GP or pharmacist.

It is also worth noting that sarcopenic obesity, where significant fat mass masks underlying muscle loss, can make lower-limb wasting less visually obvious; functional and strength measures are therefore important alongside any assessment of body composition.

Understanding the underlying cause is essential before any treatment plan is considered, as the approach differs considerably depending on whether the loss is driven by disuse, disease, hormonal change, or medication.

How do doctors diagnose muscle wasting in the lower body?

Diagnosis combines clinical examination, functional tests such as the chair-stand test and gait speed, blood tests, and specialist investigations including EMG, MRI, and DEXA scanning, guided by the EWGSOP2 framework.

Doctors diagnose muscle wasting in the lower body through a combination of clinical assessment, functional tests, and targeted investigations, with the specific pathway guided by the suspected underlying cause. There is no single definitive test; diagnosis is typically built from several complementary findings.

During a clinical examination, a GP or specialist will observe the symmetry and bulk of the thigh and gluteal muscles, compare limb circumferences, and assess muscle strength using standardised grading scales such as the Medical Research Council (MRC) scale. Gait analysis, the ability to rise from a chair without using the arms, and grip strength are commonly used functional markers that correlate well with lower-limb muscle mass. Validated screening tools such as the SARC-F questionnaire, chair-stand tests, and gait speed measurement are also used, particularly in older adults, in line with the European Working Group on Sarcopenia in Older People (EWGSOP2) framework, which assesses muscle strength first, then muscle quantity or quality, then physical performance.^[1][2]

Investigations that may be arranged in primary care include:

• Blood tests: Full blood count, inflammatory markers (CRP, ESR), thyroid function, vitamin D, renal and liver profiles, creatine kinase (CK), HbA1c or fasting glucose, and vitamin B12. These help identify systemic, endocrine, metabolic, and drug-related causes.

• Electromyography (EMG) and nerve conduction studies: These distinguish between muscle disease (myopathy) and nerve disease (neuropathy) as the source of weakness. These tests are arranged in secondary care, typically via neurology.

• MRI or ultrasound: Imaging can quantify muscle volume, detect fatty infiltration, and identify structural abnormalities in the spine or hip that may be compressing relevant nerves. These are usually arranged by a specialist.

• DEXA scan: Dual-energy X-ray absorptiometry provides an accurate measure of lean muscle mass and is used in specialist settings for the formal assessment of sarcopenia. Bioelectrical impedance analysis (BIA) is a practical alternative used in some community and outpatient settings where DEXA is not readily available.

• Muscle biopsy: Reserved for cases where an inflammatory or inherited muscle disease is suspected, and arranged by a specialist.

The British Geriatrics Society and EWGSOP2 both recommend that assessment should be holistic, incorporating objective measurements alongside the patient's reported functional limitations. If initial investigations suggest a neurological, rheumatological, or complex musculoskeletal cause, referral to the appropriate specialist team will usually follow.

Which conditions are commonly linked to leg and buttock muscle loss?

Lumbar disc disease, peripheral neuropathy, hypothyroidism, Cushing's syndrome, type 2 diabetes, inflammatory myopathies, chronic systemic illness, and long-term corticosteroid or statin use are among the most common linked conditions.

Several well-recognised medical conditions are commonly linked to muscle loss in the legs and buttocks, ranging from neurological and endocrine disorders to chronic systemic illness. Identifying the underlying condition is the cornerstone of effective management.

Neurological causes are among the most significant. Lumbar spinal stenosis and herniated intervertebral discs can compress the nerve roots supplying the quadriceps, hamstrings, and gluteal muscles, leading to neurogenic atrophy that is often asymmetrical. Peripheral neuropathy, whether caused by type 2 diabetes, alcohol excess, or vitamin B12 deficiency, can produce a similar pattern of distal and proximal weakness. Rarer conditions such as motor neurone disease and muscular dystrophies can also present with lower-limb wasting and warrant early specialist referral if suspected.

Endocrine and metabolic conditions also play an important role. Hypothyroidism slows muscle protein turnover, while hyperthyroidism can cause proximal muscle weakness and wasting. Cushing's syndrome, caused by excess cortisol, produces a characteristic pattern of proximal muscle wasting that prominently affects the thighs and buttocks.^[13] Type 2 diabetes is associated with accelerated sarcopenia, partly through insulin resistance and partly through associated neuropathy.^[19][20]

Medication-related causes are common and often overlooked. Long-term systemic corticosteroids and statins are among the medicines most frequently associated with proximal muscle weakness and wasting. If new weakness develops after starting or increasing a medicine, a review with the prescribing clinician is important.

Inflammatory muscle diseases such as polymyositis and dermatomyositis cause immune-mediated destruction of muscle fibres, with the proximal lower limb muscles frequently affected early.^[17][18] Polymyalgia rheumatica, though primarily a condition of pain and stiffness, can also contribute to functional muscle loss through disuse.

Chronic systemic illness including heart failure, chronic obstructive pulmonary disease (COPD), chronic kidney disease, and cancer-related cachexia all drive muscle catabolism through a combination of inflammation, reduced physical activity, and nutritional compromise.

Finally, age-related sarcopenia is itself a recognised clinical entity. The British Geriatrics Society and EWGSOP2 both acknowledge that sarcopenia affects a substantial proportion of adults over 65 and is associated with increased risk of falls, fractures, and loss of independence.^[14][15]

What treatments and exercises can help rebuild lost muscle?

Progressive resistance exercise, including squats, hip bridges, and step-ups, combined with a protein intake of at least 1.2 g per kg per day and treatment of the underlying cause, is the most evidence-based approach to rebuilding lost muscle.

Rebuilding lost muscle in the legs and buttocks requires a structured combination of progressive resistance exercise, adequate nutritional support, and, where appropriate, treatment of the underlying medical cause. No single intervention is sufficient on its own.

Resistance exercise is the most evidence-based intervention for reversing muscle atrophy. The UK Chief Medical Officers' Physical Activity Guidelines and NICE guidance on falls prevention in older people both support progressive resistance and strength training as a core component of maintaining and rebuilding muscle.^[5][6] Exercises particularly effective for the lower body include:

• Squats and sit-to-stand exercises: Target the quadriceps and gluteal muscles simultaneously.

• Hip bridges and glute presses: Isolate the gluteus maximus and medius with low joint stress.

• Leg press and step-ups: Allow progressive loading in a controlled manner.

• Walking and stair climbing: Provide functional, weight-bearing stimulus suitable for older adults or those recovering from illness.

Before starting a resistance programme, people with severe osteoarthritis, unstable cardiac disease, severe COPD, or significant spinal pathology should seek advice from their GP or physiotherapist to ensure the programme is safe and appropriately adapted. A physiotherapist can design a programme tailored to the individual's current strength, balance, and any co-existing conditions. NHS physiotherapy is available through a GP referral, and some NHS areas also allow self-referral; check with your local service.

Nutritional support is equally important. International expert groups including ESPEN and the PROT-AGE study group recommend a dietary protein intake of at least 1.2 grams per kilogram of body weight per day for older adults with sarcopenia or muscle wasting, with protein distributed evenly across meals to maximise muscle protein synthesis. This target may not be appropriate for people with chronic kidney disease or significant liver disease, where protein intake should be guided by a dietitian or specialist. If you are unsure about your nutritional needs, ask your GP for a referral to a registered dietitian.

Vitamin D supplementation may be recommended where deficiency is confirmed or where there is a recognised risk of deficiency, in line with NICE and SACN guidance, as low vitamin D can impair muscle function independently of its effects on bone.

Medical management of the underlying condition, whether optimising thyroid hormone replacement, controlling blood glucose in diabetes, or treating inflammatory myopathy with immunosuppressants, is essential to create the physiological environment in which exercise and nutrition can be effective.

Bolt Pharmacy is a GPhC-registered UK online pharmacy offering online consultations, with prescriber review and pharmacist support, and may be one option for those seeking clinical guidance on conditions that contribute to muscle loss.

When should you see a GP about muscle loss in your legs or buttocks?

See a GP if muscle loss is progressive, unexplained, asymmetrical, or accompanied by weakness, pain, numbness, unintentional weight loss, or falls; sudden bilateral weakness with bladder or bowel changes requires immediate emergency attendance.

You should see a GP about muscle loss in your legs or buttocks if the wasting is progressive, unexplained, associated with weakness, or accompanied by other symptoms that suggest an underlying medical condition. Muscle loss that develops gradually over months without an obvious cause such as prolonged bed rest or a known chronic illness warrants prompt assessment.

Contact your GP if you notice any of the following:

• Visible thinning or asymmetry of one or both thighs or buttocks that is worsening over weeks or months.

• Difficulty rising from a chair, climbing stairs, or walking that is new or deteriorating.

• Associated symptoms such as back or leg pain, numbness, tingling, or bladder and bowel changes, which may suggest nerve compression.

• Unintentional weight loss alongside muscle wasting, which can indicate a systemic illness including malignancy.

• Muscle pain or tenderness at rest, which may point to an inflammatory muscle condition.

• Falls or near-falls attributable to leg weakness.

• New foot drop (difficulty lifting the front of the foot), which may indicate nerve damage and warrants prompt assessment.

• Severe muscle pain or weakness with dark or cola-coloured urine, particularly after starting a new medicine such as a statin or following an infection, as this may indicate rhabdomyolysis, a condition requiring urgent medical attention.

If you develop sudden severe weakness in both legs, loss of bladder or bowel control, or numbness in the saddle area (inner thighs and perineum), these are potential signs of cauda equina syndrome, a medical emergency. In that situation, go to your nearest accident and emergency department immediately or call 999.

For non-emergency concerns that cannot wait for a routine GP appointment, NHS 111 can provide advice on the appropriate next step.

Suspected adverse effects of any medicine contributing to muscle symptoms can be reported to the MHRA via the Yellow Card scheme at yellowcard.mhra.gov.uk.

Early assessment is important because many causes of lower-limb muscle wasting are treatable, and the sooner the underlying cause is identified, the better the prospects for recovery.

Scientific References

1. Sarcopenia: revised European consensus on definition and diagnosis (EWGSOP2).
2. Sarcopenia: revised European consensus on definition and diagnosis.
3. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group.
4. SACN Vitamin D and Health Report.
5. UK Chief Medical Officers' Physical Activity Guidelines.
6. Falls: assessment and prevention in older people (NG249).
7. Statin-Induced Necrotizing Autoimmune Myositis Presenting With Progressive Limb-Girdle Weakness Following Low-Dose Atorvastatin Use.
8. Challenges in the diagnosis and management of immune-mediated necrotising myopathy (IMNM) in a patient on long-term statins.
9. Deep venous thrombosis in an individual with statin-exposed anti-SRP myopathy: case report and review of literature.
10. Statin-Associated Myopathy: Emphasis on Mechanisms and Targeted Therapy.
11. Clinical features related to statin-associated muscle symptoms.
12. Serious statin-associated myotoxicity and rhabdomyolysis in Aboriginal and Torres Strait Islanders: a case series.
13. Hypercortisolism: Causes, Consequences and Clinical Significance - A Review of Pathophysiology.
14. Epidemiology of sarcopenia: Prevalence, risk factors, and consequences.
15. The correlation between sarcopenia and osteoporosis in the elderly: a systematic review and meta-analysis.
16. Interventions with milk proteins supplementation combined with exercise on musculoskeletal function in older adults with sarcopenia, osteoporosis and osteosarcopenia: a systematic review protocol.
17. Laryngeal Complications of Dermatomyositis: A Case Report and Comprehensive Review of the Literature.
18. Beyond Hypothyroid Myopathy: Signal Recognition Particle (SRP)-Negative Necrotizing Dermatomyositis Unmasked by Anti-nuclear Matrix Protein 2 (Anti-NXP2) Positivity.
19. Sarcopenia in Diabetes: A proposal on integrating muscle assessment and nutritional intervention in people living with diabetes.
20. Protocol for a prospective cohort study for the assessment of sarcopenia in gestational diabetes: the SiGnal-D study.
21. Muscle loss and GLP-1R agonists use.
22. Hypovitaminosis D and frailty: Epiphenomenon or causal?.
23. Diagnostic accuracy of the SARC-F questionnaire in Argentine older adults.
24. Enhancing sarcopenia screening in primary care: a machine learning approach using simple physical tests vs. SARC-F in 2,788 community-dwelling older adults.
25. Muscular dystrophy.

Frequently Asked Questions