How to Interpret DEXA Scan Results?
Obtaining a Dual-Energy X-ray Absorptiometry (DEXA) scan is an excellent way to gain a precise evaluation of both your body composition and bone mineral density. These scans provide valuable insights for athletes, the general population, and those at risk of osteoporosis. With a wide range of data and detailed sections in the report, understanding your results is key to taking meaningful steps toward achieving your health and fitness objectives.
Total Body Composition Results
Colour Map
The DEXA scan provides a detailed breakdown of body composition, displayed as a colour-coded image:
- Yellow regions represent areas with a higher percentage of fat.
- Orange and red regions indicate progressively lower percentages of fat.
- Blue regions highlight areas containing bone.
This visual map allows for an easy and accurate assessment of fat distribution, lean tissue, and bone composition. It’s a powerful tool for understanding your body and monitoring changes over time.
DEXA Body Composition Measurements
DEXA is one of the most proven and reliable technologies for measuring body composition, offering comprehensive and precise insights into various aspects of your body.
Total Body Measurement:
Your body composition scan will include:
- total body bone mineral density (BMD)
- total bone mineral content (BMC)
- fat mass
- lean mass
- percentage fat.
Segmental Analysis
- All areas are defined by cut lines, with percentage fat reported per segment.
- Segments include, arms, legs, head, trunk (torso), android (waist), and gynoid (hips)
- Percent fat mass per segment
Additional Metrics
- Visceral Adipose Tissue (VAT): Fat stored around abdominal organs
- Appendicular Lean Mass (ALM): Combined lean mass in arms and legs
- Ratios and Indices:
- Android % Fat to Gynoid % Fat ratio
- Fat mass index (fat mass/height²)
- % Fat trunk to % Fat legs
- Trunk-to-limb fat mass ratio
- Lean mass index (lean mass/height²)
- Appendicular lean mass index (total lean mass in arms + legs /height²)
Bone Measurements
- Bone mineral density (BMD)
- Bone mineral content
Fat Mass
Adipose Indices
This breaks down the body fat into separate components and compares this to different demographics.
- YN (20-29 year-olds): In this example, 78% of people in that age group have a lower body fat percentage than you.
- AM (Age specific): In this example, 87% of people your age have a lower body fat percentage than you.
Body fat % can be influenced by total muscle mass (i.e. the higher your muscle mass, the lower the percentage will be, despite having the same body amount of body fat).
To account for this, the ‘Fat Mass/Height²’ indices represent how much body fat you have across your height.
Android/Gynoid Ratio: A higher A/G ratio suggests a greater proportion of fat is stored in the android region, which is associated with an increased risk of cardiovascular diseases, cancer, type 2 diabetes, and metabolic syndrome.
VAT = Visceral Adipose Tissue (the fat around the internal organs).
‘Est. VAT Area (cm²)’ represents the amount visceral fat present per squared centimeter. Interpreting results can be difficult as there is a lack of appropriate reference ranges. However, with the current research, the rages below may be used as a general guide towards identifying varying levels of health risks.
Body Fat % Graph
This graph plots your body fat percentage (white marker) in comparison to your age group (using Z – scores).
- Z Score = 0: The value is exactly at the mean.
- Z Score > 0: Indicates the value is above the mean.
- Z Score < 0: Indicates the value is below the mean.
The numbers represent standard deviations from the mean:
- About 68% of the data falls within one standard deviation of the mean (between Z scores of -1 and 1).
- About 95% of the data falls within two standard deviations of the mean (between Z scores of -2 and 2).
Lean Mass
Lean Indices
Lean/Height² = Amount of muscle mass in the body respect to your height.
Appendicular Lean/Height² = The amount of muscle mass you have not including your trunk (i.e. muscle mass in your arms and legs).
In this example, 11% of 20-29 year olds & 16% of those your age have more muscle mass than you.
Rate of Change
When you have a follow-up scan, you will receive an additional page comparing your current to your previous results.
It will highlight the overall change in body fat percentage, total fat mass, total lean mass, and total mass in grams.
Bone Mineral Density (BMD)
The first page highlights all of the relevant information regarding your BMD. This separates your data into each body compartment and provides the totals. There are also separate headings to be aware of.
- BMC: Bone mineral content i.e. the total weight of your bones.
- BMD: Bone mineral density. This is the BMC divided by the area (grams/cm²)
BMD Graph
Your BMD results are compared with two norms – a young healthy population (T-score) and age-matched (Z-score).
- T-score: Indicates how your bone density compares to the optimal or peak bone density of a healthy, young adult of the same sex. T-scores are categorized as follows:
- Above -1: Normal bone density.
- Between -1 and -2.5: Indicates osteopenia, a condition where bone density is below normal and may lead to osteoporosis.
- Below -2.5: Indicates osteoporosis, a condition characterised by weak and brittle bones.
Important to note: A whole-body bone density provides you with the total bone mass and BMD but cannot provide a diagnosis of osteoporosis.
Reference Comparison
There are numbers on the report comparing your data to certain demographics.
- YN: ‘Young Normal’ (20-29 year-olds).
- AM: ‘Age Matched’ (Age specific).
This is based off the ‘National Health & Nutrition Survey’ (NHANES) Data. It includes over 20,000 participants, aged 8-85, with the data solely collected on Hologic equipment (what we use in clinic).