Chronic Pain and Body Composition: What Your DEXA Scan Reveals About How Pain Affects Fat, Muscle, and Bone

Chronic pain affects roughly one in four adults in the United Kingdom. According to the NHS Health Survey for England 2024, 26% of adults report chronic pain, and 13% experience high-impact chronic pain that limits daily activities. What often goes unrecognised is how profoundly this pain reshapes the body itself.

When pain persists for months or years, the body adapts in ways that compound the original problem. Physical activity drops. Muscle tissue wastes. Fat accumulates, particularly around the organs. Inflammatory markers rise, which in turn heightens pain sensitivity. It is a cycle that scales and BMI readings cannot capture, but a body composition DEXA scan can.

This article explains the mechanisms that link chronic pain to measurable changes in fat, muscle, and bone, and how a DEXA scan provides the clinical data needed to intervene effectively.

The relationship between chronic pain and body composition operates through several interconnected pathways. Understanding these mechanisms is essential for anyone who has lived with persistent pain and noticed changes in their body that go beyond what the bathroom scales reveal.

The most immediate effect is reduced physical activity. Pain discourages movement, and prolonged inactivity leads to skeletal muscle atrophy. A 2023 study published in the Journal of Clinical Medicine found that patients with non-specific chronic pain lasting six months or longer had significantly lower skeletal muscle mass index and higher body fat percentage compared to age-matched controls without pain (Sakai et al., 2023). This was not simply a matter of weight gain. The composition of the body shifted: lean tissue declined while adipose tissue increased.

Medications commonly prescribed for chronic pain can accelerate these changes. Corticosteroids promote visceral fat deposition and muscle protein breakdown. Opioid analgesics suppress testosterone and growth hormone, both of which are critical for maintaining lean mass. Anticonvulsants and certain antidepressants used for neuropathic pain frequently cause weight gain through appetite stimulation and metabolic slowing.

Stress hormones add another layer. Chronic pain elevates cortisol, which preferentially directs fat storage to the abdominal region and accelerates the breakdown of muscle protein. Over months and years, these hormonal shifts produce a body composition profile that looks markedly different from what existed before the pain began.

Clinicians refer to the “pain-inactivity cycle” because it describes a self-reinforcing loop. Pain reduces movement. Reduced movement causes muscle deconditioning. Weaker muscles provide less joint support and spinal stability. This increases mechanical stress on joints and soft tissues, which generates more pain. The cycle repeats, and with each turn, the body loses more functional capacity.

Research published in Frontiers in Pain Research (2024) demonstrated that total lean mass was independently associated with lower pressure pain sensitivity in older adults. In other words, maintaining muscle appears to be directly protective against pain. Conversely, losing muscle removes that protective buffer and leaves the body more vulnerable to pain from everyday activities.

A population-based cohort study of men aged 60 and older found that higher lean mass at baseline was protective against developing high-intensity back pain over a ten-year follow-up period (Body Composition and Incident High-Intensity Back Pain, 2024). The implication is clear: muscle is not just about strength or appearance. It is a functional shield against pain, and losing it has consequences that extend well beyond reduced fitness.

The rate of muscle loss in chronic pain patients often exceeds what would be expected from ageing alone. While age-related muscle loss (sarcopenia) typically begins in the fourth decade, chronic pain can trigger comparable losses in younger individuals within months of becoming sedentary. A 35-year-old with severe chronic back pain who has been largely inactive for a year may show lean mass levels more typical of someone a decade older.

Fat tissue is not passive storage. It is metabolically active, and visceral fat (the fat surrounding your internal organs) is particularly so. Adipocytes and the macrophages that infiltrate them release inflammatory cytokines including tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and leptin. These molecules circulate systemically, amplifying inflammatory signalling throughout the body.

For someone with chronic pain, this creates a compounding problem. Inflammation from visceral fat increases peripheral and central pain sensitisation, meaning the nervous system responds more intensely to stimuli that would otherwise be tolerable. Research has shown that excess body fat, particularly in visceral and central depots, is associated not only with increased joint load and systemic inflammation but also with greater risk for cardiometabolic comorbidities that further limit physical function.

This relationship runs in both directions. Pain promotes fat gain through inactivity and hormonal disruption. Fat gain promotes more pain through inflammation and mechanical loading. A body composition DEXA scan can quantify visceral adipose tissue directly, providing a number that neither scales nor waist circumference measurements can match for accuracy. Knowing your visceral fat level gives you and your clinical team a specific, measurable target to work towards.

We explored this inflammatory pathway in detail in our article on how chronic inflammation affects body composition and what a DEXA scan reveals. The overlap between chronic pain and chronic inflammation is substantial, and addressing one often requires addressing both.

If you have chronic pain and have noticed your body changing, stepping on a scale will not tell you what has actually happened. Your weight might be stable, slightly up, or even down, and none of those outcomes captures the full picture. What matters is the ratio of lean tissue to fat tissue, where that fat sits, and whether your muscle mass is adequate to support your joints and spine.

A DEXA (dual-energy X-ray absorptiometry) scan measures three compartments simultaneously: bone mineral density, lean soft tissue mass, and fat mass. It does so regionally, breaking your body into arms, legs, trunk, and android/gynoid zones. This level of detail is critical for chronic pain patients because the changes are rarely uniform.

Someone with chronic knee osteoarthritis, for example, may show significant muscle loss in the affected leg compared to the unaffected side. A person with chronic low back pain may have lost core and paraspinal muscle mass while gaining truncal fat. These asymmetries and regional imbalances are invisible on a scale, invisible on a BMI chart, and invisible on most bioimpedance smart scales, which lack the precision to detect them reliably.

DEXA also quantifies visceral adipose tissue (VAT) in the android region, providing a direct measurement of the metabolically active fat that drives systemic inflammation. For a chronic pain patient, a high VAT reading is not just a cardiovascular risk factor. It is a potential contributor to ongoing pain sensitisation that can be targeted through specific interventions.

The scan takes approximately seven minutes, uses a very low dose of radiation (less than a day of natural background exposure), and requires no special preparation. You lie still on the scanner bed, which is particularly important for patients whose pain limits the positions they can hold. Unlike MRI, there is no enclosed tube. Unlike CT, there is no significant radiation burden.

Several common chronic pain conditions have well-documented effects on body composition. Understanding which pattern applies to you helps guide the most effective response.

Osteoarthritis is the most prevalent chronic pain condition in the UK, affecting over 10 million people. Research from the KHOALA cohort study found that patients awaiting knee replacement had body weight, BMI, total fat mass, and percentage body fat more than 15% higher than those awaiting hip replacement. In knee osteoarthritis specifically, lean mass has been shown to be protective of cartilage volume, while fat mass is damaging to it. This makes body composition monitoring with DEXA particularly valuable for tracking whether rehabilitation is preserving the muscle needed to support the joint.

Chronic low back pain accounts for 40% of all sickness absence in the NHS. Evidence suggests that fat mass, but not lean tissue mass, is related to low back pain severity. A ten-year prospective study found that higher baseline lean mass protected against developing high-intensity back pain in older men. For patients with chronic back pain, a DEXA scan can reveal whether truncal lean mass has declined to levels that compromise spinal support.

Fibromyalgia affects an estimated 1.5 to 2 million people in the UK and produces widespread musculoskeletal pain alongside fatigue and sleep disturbance. Patients with fibromyalgia frequently show reduced lean mass and increased fat mass compared to matched controls, partly driven by the severe fatigue and exercise intolerance that characterise the condition.

Inflammatory arthritis conditions such as rheumatoid arthritis produce a distinctive pattern sometimes called “rheumatoid cachexia,” where systemic inflammation drives muscle wasting even in the presence of stable or increasing weight. A bone density DEXA scan is already recommended for monitoring inflammatory arthritis patients on long-term corticosteroids, but the body composition data from the same scan can be equally informative for tracking muscle preservation.

The value of a DEXA scan for chronic pain patients lies not just in diagnosis but in directing treatment. When you know exactly how much lean mass you have, where fat has accumulated, and what your visceral fat level is, the interventions become targeted rather than generic.

Exercise prescription: A physiotherapist or exercise physiologist can use DEXA data to identify which muscle groups have atrophied most severely and design a progressive loading programme that addresses those specific deficits. If your left quadriceps shows significantly less lean mass than your right (common in unilateral knee pain), the programme can include targeted unilateral strengthening. If your trunk lean mass is low relative to your limbs, core rehabilitation takes priority.

Nutritional strategy: Maintaining or rebuilding muscle during chronic pain requires adequate protein intake, typically 1.2 to 1.6 grams per kilogram of body weight per day. DEXA data helps calibrate this target to your actual lean mass rather than your total body weight, which may overestimate needs if fat mass is elevated. If visceral fat is high, a modest caloric deficit combined with resistance exercise can reduce inflammatory load without sacrificing the muscle you are trying to preserve.

Progress monitoring: Perhaps most importantly, DEXA provides objective feedback. Chronic pain patients often struggle with motivation because traditional markers of progress (weight loss, pain reduction) can be slow or inconsistent. Seeing lean mass increase by half a kilogram over three months, or visceral fat decrease by 50 grams, provides concrete evidence that the work is producing results, even if the pain has not yet improved. Many patients find this data more motivating than any subjective measure.

Medication review: If your DEXA results show rapid muscle loss or accelerating fat gain, this data can inform conversations with your prescriber about whether current medications are contributing to unfavourable body composition changes and whether alternatives exist.

Can chronic pain really cause muscle loss?

Yes. Research confirms that patients with chronic pain lasting six months or more have significantly lower skeletal muscle mass compared to pain-free controls. This occurs through reduced physical activity, elevated cortisol, and in some cases through medications that suppress anabolic hormones. The longer pain persists without intervention, the greater the cumulative muscle loss.

Will a DEXA scan hurt if I have chronic pain?

A DEXA scan is one of the most comfortable medical imaging procedures available. You lie flat on an open padded bed for approximately seven minutes. There is no injection, no enclosed space, and no need to hold uncomfortable positions. If lying flat is difficult due to your pain condition, our clinical team can discuss modifications to make you as comfortable as possible.

How often should chronic pain patients have a DEXA scan?

An initial baseline scan is the most important step. After that, a follow-up scan every 6 to 12 months allows you and your clinical team to track whether interventions are producing measurable improvements in lean mass and reductions in visceral fat. Your clinician can advise on the most appropriate interval based on your specific situation.

Does losing weight help chronic pain?

Losing fat mass, particularly visceral fat, can reduce systemic inflammation and mechanical joint loading, both of which contribute to pain. However, losing weight through crash dieting or extreme caloric restriction often results in significant muscle loss alongside fat loss, which can make pain worse by removing the muscular support your joints depend on. A DEXA scan helps ensure that any weight loss programme is preserving lean mass while reducing fat.

Can I get a DEXA scan without a GP referral?

Yes. At DEXA London, you can book a body composition scan directly without a referral. Many chronic pain patients find it helpful to bring their DEXA results to appointments with their GP, physiotherapist, or pain specialist to inform treatment planning.

What is the difference between a body composition DEXA scan and a bone density DEXA scan?

Both use the same DEXA technology, but they measure different things. A body composition scan analyses your fat mass, lean mass, and bone mineral content across your whole body and by region. A bone density scan focuses specifically on bone mineral density at the hip and spine to assess osteoporosis risk. For chronic pain patients, both types of information can be clinically valuable.

Chronic pain changes your body in ways that scales and BMI cannot detect. A DEXA body composition scan at DEXA London provides the precise, clinical-grade data you need to understand what has changed, set meaningful targets, and track real progress over time.

Our clinic is located at 86 Harley Street, London. Scans are available Monday to Saturday with results reviewed during your appointment. To book your DEXA scan or to discuss whether a body composition or bone density assessment is right for you, call us on 0207 637 8227 or book online through our website.

Dr Emil Gadimali