How to Interpret Your DEXA Scan Results

You got a DEXA scan. You are holding the report. It is a multi-page document full of color-coded body maps, T-scores, Z-scores, percentile rankings, and regional breakdowns that look like they belong in a radiology textbook.

Nobody explained what any of it means. Here is the plain-English guide.

What a DEXA Scan Measures

DEXA (Dual-Energy X-ray Absorptiometry) uses two low-dose X-ray beams at different energy levels. Different tissues — bone, fat, and lean mass — absorb these beams differently, allowing the machine to calculate the exact composition of your body region by region.

A DEXA scan gives you three primary measurements:

1. Bone mineral density (BMD) — how dense and strong your bones are
2. Body fat percentage — total and regional fat distribution
3. Lean mass — muscle, organs, water, and connective tissue (everything that is not fat or bone)

Some DEXA reports also include visceral adipose tissue (VAT) measurements, which track the fat surrounding your internal organs — the most metabolically dangerous type of fat.

Reading Your Bone Density Results

T-Score

Your T-score compares your bone density to that of a healthy 30-year-old of the same sex. This is the gold standard measurement for bone health.

Interpreting your T-score:

• Above -1.0: Normal bone density. No action needed beyond maintaining healthy habits.
• -1.0 to -2.5: Osteopenia. Your bone density is below normal but not yet in the osteoporosis range. This is a warning zone — lifestyle interventions (resistance training, vitamin D, calcium, K2) can prevent further loss and often improve density.
• Below -2.5: Osteoporosis. Significantly reduced bone density with increased fracture risk. Medical intervention may be appropriate. Discuss with your physician.

Example: A T-score of -1.3 means your bone density is 1.3 standard deviations below the young-adult average. This is mild osteopenia — not alarming, but worth addressing.

Z-Score

Your Z-score compares your bone density to people of the same age, sex, and ethnicity. This tells you how you compare to your peers, not to a 30-year-old.

Interpreting your Z-score:

• Above -2.0: Your bone density is within the expected range for your age. Even if your T-score shows osteopenia, a normal Z-score means you are not losing bone faster than your peers.
• Below -2.0: Your bone density is below expected for your age. This may indicate an underlying condition accelerating bone loss and warrants medical evaluation.

Which score matters more? Both matter for different reasons. Your T-score tells you your absolute fracture risk. Your Z-score tells you whether something unusual is happening.

Regional Breakdown

Your report will show BMD for specific areas — typically lumbar spine, femoral neck (hip), and sometimes forearm. These areas are measured because they are the most common fracture sites and the best predictors of overall bone health.

Spine vs. hip: Some people have normal spine BMD but low hip BMD, or vice versa. The lowest reading from any site determines your overall diagnosis. If your spine T-score is -0.8 but your hip is -1.4, your clinical classification is osteopenia based on the hip reading.

Reading Your Body Composition Results

Total Body Fat Percentage

This is the number most people look at first. Your report will show total body fat as a percentage of your total body weight.

Healthy ranges (approximate):

| Age | Women (Healthy) | Men (Healthy) |

|-----|-----------------|---------------|

| 20-39 | 21-33% | 8-20% |

| 40-59 | 23-34% | 11-22% |

| 60+ | 24-36% | 13-25% |

Context matters more than the number. A 28% body fat reading in a 45-year-old woman who resistance trains and has high lean mass is very different from 28% in a sedentary 45-year-old woman with low lean mass. DEXA gives you the breakdown to understand the full picture.

Regional Fat Distribution

Your report includes a color-coded body map showing fat distribution by region — arms, legs, trunk (torso), and head. It also provides exact numbers for each region.

What to look for:

Android vs. Gynoid ratio (A/G ratio): This is the ratio of trunk fat to hip/thigh fat. It is the most important fat distribution metric on your report.

• A/G ratio below 1.0: More fat is stored in your hips and thighs (gynoid pattern). This is associated with lower metabolic risk.
• A/G ratio above 1.0: More fat is stored in your trunk/abdomen (android pattern). This is associated with higher metabolic risk, insulin resistance, and cardiovascular disease — regardless of your total body fat percentage.

Asymmetry: Your report may show differences between left and right sides. Small differences (1-3%) are normal. Larger differences may indicate a limb that is underdeveloped due to injury, disuse, or dominant-side bias.

Visceral Adipose Tissue (VAT)

If your report includes VAT measurement, this is arguably the most valuable number on the entire report. Visceral fat surrounds your organs and is metabolically active — it produces inflammatory compounds that drive insulin resistance, cardiovascular disease, and metabolic syndrome.

Interpreting VAT:

• VAT is usually reported in square centimeters (area) or volume.
• Below 100 cm²: Low risk
• 100-160 cm²: Moderate risk
• Above 160 cm²: High risk

Two people with identical total body fat percentages can have dramatically different VAT levels. A person with 25% body fat and high VAT has significantly more metabolic risk than a person with 25% body fat and low VAT.

Lean Mass

Your lean mass reading includes muscle, water, organs, and connective tissue. DEXA cannot distinguish between muscle and water within lean mass, which is important to understand.

What lean mass tells you:

• Your total lean mass relative to your height and sex indicates your muscle development
• Regional lean mass (arms, legs, trunk) shows muscle distribution
• Appendicular lean mass index (ALMI) — lean mass in your arms and legs divided by height squared — is used to screen for sarcopenia (age-related muscle loss)

ALMI reference values:

• Women: Below 5.67 kg/m² may indicate sarcopenia
• Men: Below 7.23 kg/m² may indicate sarcopenia

The lean mass caveat: If you are dehydrated, your lean mass will read lower. If you are retaining water (inflammation, sodium intake, menstrual cycle phase), lean mass will read higher. For consistent tracking, get scans under the same conditions — same time of day, similar hydration, similar diet the day before.

How to Use Your Results

If your primary goal is fat loss:

Focus on your trunk fat percentage and VAT more than total body fat. These are the highest-risk fat deposits and should decrease first with effective intervention. Monitor lean mass to ensure you are losing fat, not muscle.

Red flag: If your total weight is decreasing but your lean mass is also decreasing, you are losing muscle along with fat. This usually means insufficient protein intake or no resistance training.

If your primary goal is building muscle:

Track appendicular lean mass (arms and legs) over time. Total lean mass can fluctuate with water retention, but consistent increases in appendicular lean mass over 6-12 months indicate real muscle growth.

If your primary goal is bone health:

Focus on T-scores at the spine and hip. If you are in the osteopenia range, retest in 1-2 years to track the trend. A stable T-score is a success — bone density naturally declines with age, so maintaining your current level means your interventions are working.

For general health optimization:

Your A/G ratio and VAT are the strongest predictors of metabolic health on the report. Improving these metrics — even without changing total body weight — reduces disease risk more than weight loss alone.

How Often to Get Scanned

For body composition tracking: Every 6-12 months. Shorter intervals do not show meaningful change because lean mass and fat mass shift slowly. Month-to-month scans will be dominated by hydration and glycogen fluctuations, not real body composition changes.

For bone density monitoring: Every 1-2 years if you are in the osteopenia range. Annually if you are being treated for osteoporosis. The National Osteoporosis Foundation recommends screening every 2 years for women over 65 and postmenopausal women with risk factors.

Consistency matters: Always use the same DEXA facility and ideally the same machine. Different machines can produce slightly different readings. The trend over time on the same machine is more meaningful than any single reading.

Key Takeaways

• T-score measures bone density against a healthy 30-year-old: above -1.0 is normal, -1.0 to -2.5 is osteopenia, below -2.5 is osteoporosis
• A/G ratio (trunk fat vs hip/thigh fat) is a stronger predictor of metabolic risk than total body fat percentage
• Visceral fat (VAT) is the single most dangerous fat measurement — two people with the same body fat percentage can have very different health risks based on VAT
• Lean mass includes water, so scan under consistent conditions for accurate tracking
• Get scans every 6-12 months for body composition, every 1-2 years for bone density
• Use the same DEXA machine each time — the trend matters more than any single number

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