When you step on a bathroom scale, you see a single number. But that number doesn't tell you how much of your weight comes from muscle, fat, or bone, or how those tissues might be changing over time.
For example, someone who starts strength training might lose body fat and gain muscle without seeing much change on the scale. Someone else might maintain the same weight for years while gradually losing muscle mass.
A DEXA scan can help reveal some of these changes. The technology is also used to assess bone density, helping physicians identify osteoporosis and evaluate fracture risk.
Although both tests use the same technology, they answer different questions. Here's what DEXA scanning measures, who might benefit, and how it fits into preventative healthcare in Calgary.
What Is a DEXA Scan?
DEXA (also written DXA) stands for dual-energy X-ray absorptiometry. It uses two low-dose X-ray beams to measure how different tissues in the body absorb energy. Bone, fat, and lean tissue absorb these beams differently, allowing the scanner to estimate their amounts.
The procedure is straightforward. You lie on a padded table while a scanning arm moves over your body. There's no injection, no enclosed tunnel, and no discomfort associated with the scan itself. Depending on the type of assessment, the scan generally takes around 10–20 minutes.
Radiation exposure from DEXA is very low, typically much lower than that of many other medical imaging procedures. However, because the scan uses X-rays, you should let your healthcare provider know if you are pregnant or think you might be pregnant.
There are two main applications of DEXA technology: measuring bone mineral density and assessing body composition.
Bone Density: What Does a DEXA Scan Show?
A bone density scan measures the mineral content of your bones, typically at the hip and lumbar spine. This helps physicians identify osteoporosis, a condition in which bones become weaker and more susceptible to fractures.
Bone density results are often expressed as a T-score, which compares your bone mineral density with that of a healthy young adult.
For postmenopausal women and men aged 50 and older, T-scores are generally classified as follows:
-1.0 or higher: Normal bone density
Between -1.0 and -2.5: Low bone mass (sometimes called osteopenia)
-2.5 or lower: Osteoporosis
However, bone density is only one factor influencing fracture risk.
Your physician may also consider your age, previous fractures, family history, medications, and other health conditions. These factors can be incorporated into a tool called FRAX, which estimates your probability of experiencing a major osteoporotic fracture over the next 10 years.
Osteoporosis Canada's 2023 clinical practice guideline recommends FRAX for fracture risk assessment.
This is particularly important because osteoporosis often develops without noticeable symptoms. For many people, the first indication of weakened bones is a fracture following a relatively minor fall or injury.
DEXA can identify reduced bone density before a fracture occurs and, when repeated at appropriate intervals, can help physicians monitor changes over time.
Body Composition: Looking Beyond the Scale
A whole-body DEXA scan provides a different type of information. Rather than focusing primarily on bone density, it estimates how your body weight is distributed among three components:
Fat mass: The amount of body fat you carry
Lean mass: Primarily muscle and other non-fat soft tissues, including organs and water
Bone mineral content: The mineral component of your bones
The scan also shows how fat and lean tissue are distributed throughout different regions of your body, including your arms, legs, and trunk.
This provides considerably more detail than body weight or body mass index (BMI) alone.
Consider someone who begins a strength-training program. After six months, their weight has barely changed, which might suggest that little progress has been made.
However, a body composition scan could reveal that they've lost fat while gaining lean mass. Although the number on the scale remains similar, their body composition has changed.
DEXA can also provide insight into fat distribution.
Fat stored around the abdomen, particularly visceral fat surrounding internal organs, is associated with increased risk of conditions such as type 2 diabetes and cardiovascular disease. Many modern DEXA scanners can estimate visceral fat, providing additional information that may be useful when evaluating metabolic health.
DEXA is a well-established method for assessing body composition, but it isn't perfect. Hydration, recent food intake, positioning, and differences between scanners can influence results. It also measures lean tissue rather than muscle exclusively.
For this reason, DEXA is most useful for tracking meaningful trends over time, rather than focusing on small changes between individual measurements.
Who Should Have a Bone Density Test?
Bone density testing is an established screening and diagnostic tool for people at increased risk of osteoporosis and fractures.
According to Osteoporosis Canada's 2023 clinical practice guideline, bone mineral density testing is recommended for postmenopausal women and men who are:
70 years or older, regardless of other risk factors
65–69 years old, with at least one clinical risk factor for fracture
50–64 years old, with a previous fragility fracture or at least two clinical risk factors
Important risk factors considered in screening decisions include:
A previous fracture resulting from a minor fall or injury
A parent who has experienced a hip fracture
Prolonged use of oral glucocorticoid medications, such as prednisone
Two or more falls within the past year
Current smoking
Consuming three or more alcoholic drinks per day
Low body weight or a BMI below 20
Certain medical conditions, including rheumatoid arthritis, hyperthyroidism, and disorders affecting nutrient absorption, can also contribute to bone loss and may warrant further assessment.
These recommendations primarily apply to postmenopausal women and men aged 50 and older. However, younger adults may also require bone density testing when specific medical conditions, medications, or other risk factors are present.
If you're unsure whether testing is appropriate, your family physician can assess your individual risk and help determine whether a scan would be beneficial.
Who Might Benefit From Body Composition Scanning?
Unlike bone density testing, whole-body composition scanning isn't a routinely recommended screening test for the general population.
Its greatest value comes when the results can help guide decisions about nutrition, physical activity, or other aspects of healthcare.
Some people who may benefit include:
People working on metabolic health
Body composition and fat distribution can provide additional context when managing risk factors such as elevated blood sugar, cholesterol, or blood pressure. These measurements complement, rather than replace, established clinical assessments.
People experiencing menopause or age-related changes
Changes in hormones and aging can influence muscle mass, fat distribution, and bone health. Body composition measurements may help identify changes worth addressing through nutrition and exercise.
People losing weight
Weight loss doesn't always mean fat loss. Some people also lose lean tissue, particularly during periods of rapid weight reduction. This can be relevant for individuals using weight-loss medications or following calorie-restricted diets.
DEXA may help evaluate whether changes in body weight are primarily coming from fat or lean tissue.
People participating in strength training or athletic programs
Body composition scans can provide a useful baseline for people looking to gain muscle, reduce body fat, or monitor changes associated with training.
However, improvements in strength and physical performance remain important measures of progress, even when body composition changes are modest.
People focused on healthy aging
Maintaining muscle mass and physical function becomes increasingly important as we age. Monitoring body composition alongside measures of strength, mobility, and fitness can help inform strategies for maintaining independence and long-term health.
In each of these situations, the value of the scan depends on how the information is used.
A measurement alone rarely changes someone's health. But when interpreted alongside other clinical findings and used to guide a practical plan, it can become a useful tool for monitoring progress.
DEXA Scanning in Calgary: What Does Alberta Health Cover?
In Alberta, bone mineral density testing is generally covered by the Alberta Health Care Insurance Plan (AHCIP) when medically indicated and ordered by an authorized healthcare provider.
These scans are available through community diagnostic imaging facilities, typically with a requisition from a physician or other authorized provider.
Whether a scan is covered depends on the clinical indication and applicable provincial criteria.
Repeat testing is not necessarily required every year or two. The appropriate interval depends on factors such as your initial bone density, overall fracture risk, medications, and whether you're receiving osteoporosis treatment.
For many people at lower risk who aren't receiving osteoporosis medication, repeat testing may not be necessary for several years. Others may benefit from more frequent monitoring.
Your physician can help determine the appropriate timing.
Whole-body DEXA scans performed for body composition assessment are different.
When these scans are requested for general wellness, fitness, or performance monitoring, they are generally not covered by AHCIP. They may instead be available through private imaging providers or as part of a preventative health program.
How to Prepare for a DEXA Scan
DEXA scanning usually requires very little preparation. However, instructions may differ depending on whether you're undergoing bone density testing or a whole-body composition assessment.
A few general recommendations include:
Wear comfortable clothing without metal zippers, buttons, or other accessories near the area being scanned.
Follow the imaging clinic's instructions regarding supplements. You may be asked to avoid calcium supplements for 24 hours before a bone density scan.
Inform the clinic if you've recently undergone imaging involving barium or contrast material, as this may affect the timing of your scan.
For body composition assessments, try to maintain similar conditions between scans, including hydration and meal timing, to improve the consistency of your results.
Your imaging provider will give you specific instructions before your appointment.
How Roxboro Uses DEXA
At Roxboro Clinic, we believe that understanding your health involves looking beyond any single measurement. DEXA scanning is one of the tools we may incorporate into our preventative health assessments, depending on your individual health needs and clinical indications.
When appropriate, DEXA results are reviewed alongside your bloodwork, medical history, and comprehensive fitness assessment completed through our partnership with the University of Calgary's CTEP Lab.
Together, these assessments can help us understand not only your body composition, but also how your body is functioning.
For example, a scan might identify lower-than-expected lean mass, while your fitness assessment provides additional insight into your strength and physical performance. Your physician, dietitian, and exercise physiologist can use these findings to help develop an appropriate nutrition and exercise plan.
The same approach applies to bone health. If a scan identifies reduced bone density, your physician can assess your overall fracture risk and determine whether additional monitoring, lifestyle changes, or treatment may be appropriate.
The goal isn't simply to collect more health data. It's to understand what that information means for you and use it to make informed decisions about your health.
When follow-up testing is appropriate, it can help evaluate your progress and guide adjustments to your care plan. The timing and type of repeat testing depend on your individual needs.
If you're interested in learning more about how DEXA scanning fits into Roxboro's approach to preventative care, book a discovery call with our team.
